path: root/doc/rfc/rfc4730.txt

Network Working Group                                          E. Burger
Request for Comments: 4730                      Cantata Technology, Inc.
Category: Standards Track                                       M. Dolly
                                                               AT&T Labs
                                                           November 2006


           A Session Initiation Protocol (SIP) Event Package
                     for Key Press Stimulus (KPML)

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The IETF Trust (2006).

Abstract

   This document describes a SIP Event Package "kpml" that enables
   monitoring of Dual Tone Multi-Frequency (DTMF) signals and uses
   Extensible Markup Language (XML) documents referred to as Key Press
   Markup Language (KPML).  The kpml Event Package may be used to
   support applications consistent with the principles defined in the
   document titled "A Framework for Application Interaction in the
   Session Initiation Protocol (SIP)".  The event package uses SUBSCRIBE
   messages and allows for XML documents that define and describe filter
   specifications for capturing key presses (DTMF Tones) entered at a
   presentation-free User Interface SIP User Agent (UA).  The event
   package uses NOTIFY messages and allows for XML documents to report
   the captured key presses (DTMF tones), consistent with the filter
   specifications, to an Application Server.  The scope of this package
   is for collecting supplemental key presses or mid-call key presses
   (triggers).












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RFC 4730                          KPML                     November 2006


Table of Contents

   1. Introduction ....................................................4
      1.1. Conventions Used in This Document ..........................5
   2. Protocol Overview ...............................................5
   3. Key Concepts ....................................................6
      3.1. Subscription Duration ......................................6
      3.2. Timers .....................................................7
      3.3. Pattern Matches ............................................8
      3.4. Digit Suppression .........................................12
      3.5. User Input Buffer Behavior ................................14
      3.6. DRegex ....................................................16
           3.6.1. Overview ...........................................16
           3.6.2. Operation ..........................................18
      3.7. Monitoring Direction ......................................20
      3.8. Multiple Simultaneous Subscriptions .......................20
   4. Event Package Formal Definition ................................21
      4.1. Event Package Name ........................................21
      4.2. Event Package Parameters ..................................21
      4.3. SUBSCRIBE Bodies ..........................................22
      4.4. Subscription Duration .....................................22
      4.5. NOTIFY Bodies .............................................22
      4.6. Subscriber Generation of SUBSCRIBE Requests ...............22
      4.7. Notifier Processing of SUBSCRIBE Requests .................23
      4.8. Notifier Generation of NOTIFY Requests ....................25
      4.9. Subscriber Processing of NOTIFY Requests ..................27
      4.10. Handling of Forked Requests ..............................28
      4.11. Rate of Notifications ....................................28
      4.12. State Agents and Lists ...................................28
      4.13. Behavior of a Proxy Server ...............................29
   5. Formal Syntax ..................................................29
      5.1. DRegex ....................................................29
      5.2. KPML Request ..............................................30
      5.3. KPML Response .............................................33
   6. Enumeration of KPML Status Codes ...............................34
   7. IANA Considerations ............................................34
      7.1. SIP Event Package Registration ............................34
      7.2. MIME Media Type application/kpml-request+xml ..............35
      7.3. MIME Media Type application/kpml-response+xml .............35
      7.4. URN Sub-Namespace Registration for
           urn:ietf:xml:ns:kpml-request ..............................35
      7.5. URN Sub-Namespace Registration for
           urn:ietf:xml:ns:kpml-response .............................36
      7.6. KPML Request Schema Registration ..........................37
      7.7. KPML Response Schema Registration .........................37
   8. Security Considerations ........................................37
   9. Examples .......................................................38
      9.1. Monitoring for Octothorpe .................................38



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      9.2. Dial String Collection ....................................39
   10. Call Flow Examples ............................................40
      10.1. Supplemental Digits ......................................40
      10.2. Multiple Applications ....................................45
   11. References ....................................................52
      11.1. Normative References .....................................52
      11.2. Informative References ...................................53
   Appendix A.  Contributors .........................................54
   Appendix B.  Acknowledgements .....................................54










































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RFC 4730                          KPML                     November 2006


1.  Introduction

   This document describes a SIP Event Package "kpml" that enables
   monitoring of key presses and utilizes XML documents referred to as
   Key Press Markup Language (KPML).  KPML is a markup [14] that enables
   presentation-free User Interfaces as described in the Application
   Interaction Framework [15].  The Key Press Stimulus Package is a SIP
   Event Notification Package [5] that uses the SUBSCRIBE and NOTIFY
   methods of SIP.  The subscription filter and notification report
   bodies use the Keypad Markup Language, KPML.

   The "kpml" event package requires the definition of two new MIME
   types, two new URN sub-namespaces, and two schemas for the KPML
   Request and the KPML Response.  The scope of this package is for
   collecting supplemental key presses or mid-call key presses
   (triggers).  This capability allows an Application Server service
   provider to monitor (filter) for a set of DTMF patterns at a SIP User
   Agent located in either an end-user device or a gateway.

   In particular, the "kpml" event package enables "dumb phones" and
   "gateways" that receive signals from dumb phones to report user key-
   press events.  Colloquially, this mechanism provides for "digit
   reporting" or "Dual Tone Multi-Frequency (DTMF) reporting."  The
   capability eliminates the need for "hair-pinning" (routing media into
   and then out of the same device) through a Media Server or
   duplicating all the DTMF events, when an Application Server needs to
   trigger mid-call service processing on DTMF digit patterns.

   A goal of KPML is to fit in an extremely small memory and processing
   footprint.

   The name of the XML document, KPML, reflects its legacy support role.
   The public switched telephony network (PSTN) accomplished signaling
   by transporting DTMF tones in the bearer channel (in-band signaling)
   from the user terminal to the local exchange.

   Voice-over-IP networks transport in-band signals with actual DTMF
   waveforms or RFC 2833 [10] packets.  In RFC 2833, the signaling
   application inserts RFC 2833 named signal packets as well as, or
   instead of, generating tones in the media path.  The receiving
   application receives the signal information in the media stream.

   RFC 2833 tones are ideal for conveying telephone-events point-to-
   point in a Real-time Transport Protocol (RTP) stream, as in the
   context of straightforward sessions like a 2-party call or a simple,
   centrally mixed conference.  However, there are other environments
   where additional or alternative requirements are needed.  These other
   environments include protocol translation and complex call control.



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RFC 4730                          KPML                     November 2006


   An interested application could request notifications of every key
   press.  However, many of the use cases for such signaling show that
   most applications are interested in only one or a few keystrokes.
   Thus a mechanism is needed for specifying to the user's interface
   what stimuli the application requires.

1.1.  Conventions Used in This Document

   RFC 2119 [1] provides the interpretations for the key words "MUST",
   "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT",
   "RECOMMENDED", "MAY", and "OPTIONAL" found in this document.

   The Application Interaction Framework document [15] provides the
   interpretations for the terms "User Device", "SIP Application", and
   "User Input".  This document uses the term "Application" and
   "Requesting Application" interchangeably with "SIP Application".

   Additionally, the Application Interaction Framework document
   discusses User Device Proxies.  A common instantiation of a User
   Device Proxy is a Public Switched Telephone Network (PSTN) gateway.
   Because the normative behavior of a presentation-free User Interface
   is identical for a presentation-free SIP User Agent and a
   presentation-free User Device Proxy, this document uses "User Device"
   for both cases.

2.  Protocol Overview

   The "kpml" event package uses explicit subscription notification
   requests using the SIP SUBSCRIBE and NOTIFY methods.  An Application
   that wants to collect digits creates an application/kpml-request+xml
   document with the digit patterns of interest to the Application and
   places this document in its SUBSCRIBE request.  SIP SUBSCRIBE
   messages are routed to the User Interface using standard SIP request
   routing.  KPML Subscriptions do not fork.  The KPML request contained
   in the SUBSCRIBE message identifies the target media stream by
   referencing the dialog identifiers corresponding to the session
   responsible for the media stream.  Once a subscription is
   established, the User Interface sends application/kpml-response+xml
   documents in NOTIFY requests when digits are collected or when
   timeouts or errors occur.

   A KPML subscription can be persistent or one-shot.  Persistent
   requests are active until the subscription terminates, the
   Application replaces the request, the Application deletes the request
   by sending a null document on the dialog, or the Application
   explicitly deletes the subscription by sending a SUBSCRIBE with an
   expires value of zero (0).




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RFC 4730                          KPML                     November 2006


   One-shot requests terminate the subscription upon the receipt of DTMF
   values that provide a match.  The "persist" KPML element specifies
   whether the subscription remains active for the duration specified in
   the SUBSCRIBE message or if it automatically terminates upon a
   pattern match.

   NOTIFY messages can contain XML documents.  If the User Interface
   matches a digitmap, the NOTIFY message (response) contains an XML
   document that indicates the User Input detected and whether the User
   Interface suppressed the representation of User Input, such as tones,
   or RFC 2833, from the media streams.  If the User Interface
   encountered an error condition, such as a timeout, this will also be
   reported.

3.  Key Concepts

3.1.  Subscription Duration

   KPML recognizes two types of subscriptions: one-shot and persistent.
   Persistent subscriptions have two sub-types: continuous notify and
   single-notify.

   One-shot subscriptions terminate after a pattern match occurs and a
   report is issued in a NOTIFY message.  If the User Interface detects
   a key press stimulus that triggers a one-shot KPML event, then the
   User Interface (notifier) MUST set the "Subscription-State" in the
   NOTIFY message to "terminated".  At this point, the User Interface
   MUST consider the subscription expired.

   Persistent subscriptions remain active at the User Interface, even
   after a match.  For continuous-notify persistent subscriptions, the
   User Interface will emit a NOTIFY message whenever the User Input
   matches a subscribed pattern.  For single-notify persistent
   subscriptions, the user device will emit a NOTIFY message at the
   first match, but will not emit further NOTIFY messages until the
   Application issues a new subscription request on the subscription
   dialog.

      NOTE: The single-notify persistent subscription enables lock-step
      (race-free) quarantining of User Input between different digit
      maps.

   The "persist" attribute to the <pattern> tag in the KPML subscription
   body affects the lifetime of the subscription.

   If the "persist" attribute is "one-shot", then once there is a match
   (or no match is possible), the subscription ends after the User
   Interface notifies the Application.



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   If the "persist" attribute is "persist" or "single-notify", then the
   subscription ends when the Application explicitly ends it or the User
   Interface terminates the subscription.

   If the User Interface does not support persistent subscriptions, it
   returns a NOTIFY message with the KPML status code set to 531.  If
   there are digits in the buffer and the digits match an expression in
   the SUBSCRIBE filter, the User Interface prepares the appropriate
   NOTIFY response message.

   The values of the "persist" attribute are case sensitive.

3.2.  Timers

   To address the various key press collection scenarios, three timers
   are defined.  They are the extra, critical, and inter-digit timers.

   o  The inter-digit timer is the maximum time to wait between digits.
      Note: unlike Media Gateway Control Protocol (MGCP) [11] or H.248
      [12], there is no start timer, as that concept does not apply in
      the KPML context.

   o  The critical timer is the time to wait for another digit if the
      collected digits can match more than one potential pattern.

   o  The extra timer is the time to wait for another digit if the
      collected digits can only match one potential pattern, but a
      longer match for this pattern is possible.

   The User Interface MAY support an inter-digit timeout value.  This is
   the amount of time the User Interface will wait for User Input before
   returning a timeout error result on a partially matched pattern.  The
   application can specify the inter-digit timeout as an integer number
   of milliseconds by using the "interdigittimer" attribute to the
   <pattern> tag.  The default is 4000 milliseconds.  If the User
   Interface does not support the specification of an inter-digit
   timeout, the User Interface MUST silently ignore the specification.
   If the User Interface supports the specification of an inter-digit
   timeout, but not to the granularity specified by the value presented,
   the User Interface MUST round up the requested value to the closest
   value it can support.

   The purpose of the inter-digit timeout is to protect applications
   from starting to match a pattern, yet never returning a result.  This
   can occur, for example, if the user accidentally enters a key that
   begins to match a pattern.  However, since the user accidentally
   entered the key, the rest of the pattern never comes.  Moreover, when
   the user does enter a pattern, since they have already entered a key,



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   the pattern may not match or may not match as expected.  Likewise,
   consider the case where the user thinks they entered a key press, but
   the User Interface does not detect the key.  This could occur when
   collecting ten digits, but the device actually only receives 9.  In
   this case, the User Interface will wait forever for the tenth key
   press, while the user becomes frustrated wondering why the
   application is not responding.

   The User Interface MAY support a critical-digit timeout value.  This
   is the amount of time the User Interface will wait for another key
   press when it already has a matched <regex> but there is another,
   longer <regex> that may also match the pattern.  The application can
   specify the critical-digit timeout as an integer number of
   milliseconds by using the "criticaldigittimer" attribute to the
   <pattern> tag.  The default is 1000 milliseconds.

   The purpose of the critical-digit timeout is to allow the application
   to collect longer matches than the shortest presented.  This is
   unlike MGCP [11], where the shortest match gets returned.  For
   example, if the application registers for the patterns "0011", "011",
   "00", and "0", the critical-digit timeout enables the User Interface
   to distinguish between "0", "00", "011", and "0011".  Without this
   feature, the only value that the User Interface can detect is "0".

   The User Interface MAY support an extra-digit timeout value.  This is
   the amount of time the User Interface will wait for another key press
   when it already has matched the longest <regex>.  The application can
   specify the extra-digit timeout as an integer number of milliseconds
   by using the "extradigittimer" attribute to the <pattern> tag.  The
   default is 500 milliseconds.  If there is no enterkey specified, then
   the User Interface MAY default the exteradigittimer to zero.

   The purpose of the extra-digit timeout is to allow the User Interface
   to collect the enterkey.  Without this feature, the User Interface
   would match the pattern, and the enterkey would be buffered and
   returned as the next pattern.

3.3.  Pattern Matches

   During the subscription lifetime, the User Interface may detect a key
   press stimulus that triggers a KPML event.  In this case, the User
   Interface (notifier) MUST return the appropriate KPML document.

   The pattern matching logic works as follows.  KPML User Interfaces
   MUST follow the logic presented in this section so that different
   implementations will perform deterministically on the same KPML
   document given the same User Input.




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RFC 4730                          KPML                     November 2006


   A kpml request document contains a <pattern> element with a series of
   <regex> tags.  Each <regex> element specifies a potential pattern for
   the User Interface to match.  The Section 5.1 describes the DRegex,
   or digit regular expression, language.

   The pattern match algorithm matches the longest regular expression.
   This is the same mode as H.248.1 [12] and not the mode presented by
   MGCP [11].  The pattern match algorithm choice has an impact on
   determining when a pattern matches.  Consider the following KPML
   document.

   <?xml version="1.0" encoding="UTF-8"?>
   <kpml-request xmlns="urn:ietf:params:xml:ns:kpml-request"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation=
           "urn:ietf:params:xml:ns:kpml-request kpml-request.xsd"
         version="1.0">
     <pattern>
       <regex>0</regex>
       <regex>011</regex>
     </pattern>
   </kpml-request>

                         Figure 1: Greedy Matching

   In Figure 1, if we were to match on the first found pattern, the
   string "011" would never match.  This happens because the "0" rule
   would match first.

   While this behavior is what most applications desire, it does come at
   a cost.  Consider the following KPML document snippet.

     <regex>x{7}</regex>
     <regex>x{10}</regex>

                        Figure 2: Timeout Matching

   Figure 2 shows a typical North American dial plan.  From an
   application perspective, users expect a seven-digit number to respond
   quickly, not waiting the typical inter-digit critical timer (usually
   four seconds).  Conversely, the user does not want the system to cut
   off their ten-digit number at seven digits because they did not enter
   the number fast enough.

   One approach to this problem is to have an explicit dial string
   terminator.  Often, it is the pound key (#).  Now, consider the
   following snippet.




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RFC 4730                          KPML                     November 2006


   <regex>x{7}#</regex>
   <regex>x{10}#</regex>

                   Figure 3: Timeout Matching with Enter

   The problem with the approach in Figure 3 is that the "#" will appear
   in the returned dial string.  Moreover, one often wants to allow the
   user to enter the string without the dial string termination key.  In
   addition, using explicit matching on the key means one has to double
   the number of patterns, e.g., "x{7}", "x{7}#", "x{10}", and "x{10}#".

   The approach used in KPML is to have an explicit "Enter Key", as
   shown in the following snippet.

   <pattern enterkey="#">
     <regex>x{7}</regex>
     <regex>x{10}</regex>
   </pattern>

                 Figure 4: Timeout Matching with Enter Key

   In Figure 4, the enterkey attribute to the <pattern> tag specifies a
   string that terminates a pattern.  In this situation, if the user
   enters seven digits followed by the "#" key, the pattern matches (or
   fails) immediately.  KPML indicates a terminated nomatch with a KPML
   status code 402.

      NOTE: The enterkey is a string.  The enterkey can be a sequence of
      key presses, such as "**".

   Some patterns look for long-duration key presses.  For example, some
   applications look for long "#" or long "*".

   KPML uses the "L" modifier to <regex> characters to indicate long key
   presses.  The following KPML document looks for a long pound of at
   least 3 seconds.















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RFC 4730                          KPML                     November 2006


   <?xml version="1.0" encoding="UTF-8"?>
   <kpml-request xmlns="urn:ietf:params:xml:ns:kpml-request"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation=
           "urn:ietf:params:xml:ns:kpml-request kpml-request.xsd"
         version="1.0">
     <pattern long="3000">
       <regex>L#</regex>
     </pattern>
   </kpml-request>

                                Long Pound

   The request can specify what constitutes "long" by setting the long
   attribute to the <pattern>.  This attribute is an integer
   representing the number of milliseconds.  If the user presses a key
   for longer than "long" milliseconds, the Long modifier is true.  The
   default length of the long attribute is 2500 milliseconds.

   User Interfaces MUST distinguish between long and short input when
   the KPML document specifies both in a document.  However, if there is
   not a corresponding long key press pattern in a document, the User
   Interface MUST match the key press pattern irrespective of the length
   of time the user presses the key.

   As an example, in the following snippet in Figure 6, the User
   Interface discriminates between a long "*" and a normal "*", but any
   length "#" will match the pattern.

   <pattern>
     <regex tag="short_star">*</regex>
     <regex tag="long_star">L*</regex>
     <regex>#</regex>
   </pattern>

                     Figure 6: Long and Short Matching

   Some User Interfaces are unable to present long key presses.  An
   example is an old private branch exchange (PBX) phone set that emits
   fixed-length tones when the user presses a key.  To address this
   issue, the User Interface MAY interpret a succession of presses of a
   single key to be equivalent to a long key press of the same key.  The
   Application indicates it wants this behavior by setting the
   "longrepeat" attribute to the <pattern> to "true".

   The KPML document specifies if the patterns are to be persistent by
   setting the "persist" attribute to the <pattern> tag to "persist" or
   "single-notify".  Any other value, including "one-shot", indicates



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   the request is a one-shot subscription.  If the User Interface does
   not support persistent subscriptions, it returns a KPML document with
   the KPML status code set to 531.  If there are digits in the buffer
   and the digits match an expression in the KPML document, the User
   Interface emits the appropriate kpml notification.

   Note the values of the "persist" attribute are case sensitive.

   Some User Interfaces may support multiple regular expressions in a
   given pattern request.  In this situation, the application may wish
   to know which pattern triggered the event.

   KPML provides a "tag" attribute to the <regex> tag.  The "tag" is an
   opaque string that the User Interface sends back in the notification
   report upon a match in the digit map.  In the case of multiple
   matches, the User Interface MUST choose the longest match in the KPML
   document.  If multiple matches match the same length, the User
   Interface MUST choose the first expression listed in the subscription
   KPML document based on KPML document order.

   If the User Interface cannot support multiple regular expressions in
   a pattern request, the User Interface MUST return a KPML document
   with the KPML status code set to 532.  If the User Interface cannot
   support the number of regular expressions in the pattern request, the
   User Interface MUST return a KPML document with the KPML status code
   set to 534.

      NOTE: We could mandate a minimum number of regular expressions
      that a User Interface must support per subscription request and
      globally.  However, such minimums tend to become designed-in,
      hard-coded limits.  For guidance, one should be able to easily
      handle tens of expressions per subscription and thousands
      globally.  A good implementation should have effectively no
      limits.  That said, to counter possible denial-of-service attacks,
      implementers of User Interfaces should be aware of the 534 and 501
      status codes and feel free to use them.

3.4.  Digit Suppression

   Under basic operation, a KPML User Interface will transmit in-band
   tones (RFC 2833 [10] or actual tone) in parallel with User Input
   reporting.

      NOTE: If KPML did not have this behavior, then a User Interface
      executing KPML could easily break called applications.  For
      example, take a personal assistant that uses "*9" for attention.
      If the user presses the "*" key, KPML will hold the digit, looking
      for the "9".  What if the user just enters a "*" key, possibly



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      because they accessed an interactive voice response (IVR) system
      that looks for "*"?  In this case, the "*" would get held by the
      User Interface, because it is looking for the "*9" pattern.  The
      user would probably press the "*" key again, hoping that the
      called IVR system just did not hear the key press.  At that point,
      the User Interface would send both "*" entries, as "**" does not
      match "*9".  However, that would not have the effect the user
      intended when they pressed "*".

   On the other hand, there are situations where passing through tones
   in-band is not desirable.  Such situations include call centers that
   use in-band tone spills to initiate a transfer.

   For those situations, KPML adds a suppression tag, "pre", to the
   <regex> tag.  There MUST NOT be more than one <pre> tag in any given
   <regex> tag.

   If there is only a single <pattern> and a single <regex>, suppression
   processing is straightforward.  The end-point passes User Input until
   the stream matches the regular expression <pre>.  At that point, the
   User Interface will continue collecting User Input, but will suppress
   the generation or pass-through of any in-band User Input.

   If the User Interface suppressed stimulus, it MUST indicate this by
   including the attribute "suppressed" with a value of "true" in the
   notification.

   Clearly, if the User Interface is processing the KPML document
   against buffered User Input, it is too late to suppress the
   transmission of the User Input, as the User Interface has long sent
   the stimulus.  This is a situation where there is a <pre>
   specification, but the "suppressed" attribute will not be "true" in
   the notification.  If there is a <pre> tag that the User Interface
   matched and the User Interface is unable to suppress the User Input,
   it MUST set the "suppressed" attribute to "false".

   A KPML User Interface MAY perform suppression.  If it is not capable
   of suppression, it ignores the suppression attribute.  It MUST set
   the "suppressed" attribute to "false".  In this case, the pattern to
   match is the concatenated pattern of pre+value.

   At some point in time, the User Interface will collect enough User
   Input to the point it matches a <pre> pattern.  The interdigittimer
   attribute indicates how long to wait for the user to enter stimulus
   before reporting a time-out error.  If the interdigittimer expires,
   the User Interface MUST issue a time-out report, transmit the
   suppressed User Input on the media stream, and stop suppression.




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   Once the User Interface detects a match and it sends a NOTIFY request
   to report the User Input, the User Interface MUST stop suppression.
   Clearly, if subsequent User Input matches another <pre> expression,
   then the User Interface MUST start suppression.

   After suppression begins, it may become clear that a match will not
   occur.  For example, take the expression

   <regex><pre>*8</pre>xxx[2-9]xxxxxx</regex>

   At the point the User Interface receives "*8", it will stop
   forwarding stimulus.  Let us say that the next three digits are
   "408".  If the next digit is a zero or one, the pattern will not
   match.

      NOTE: It is critically important for the User Interface to have a
      sensible inter-digit timer.  This is because an errant dot (".")
      may suppress digit sending forever.

   Applications should be very careful to indicate suppression only when
   they are fairly sure the user will enter a digit string that will
   match the regular expression.  In addition, applications should deal
   with situations such as no-match or time-out.  This is because the
   User Interface will hold digits, which will have obvious User
   Interface issues in the case of a failure.

3.5.  User Input Buffer Behavior

   User Interfaces MUST buffer User Input upon receipt of an
   authenticated and accepted subscription.  Subsequent KPML documents
   apply their patterns against the buffered User Input.  Some
   applications use modal interfaces where the first few key presses
   determine what the following key presses mean.  For a novice user,
   the application may play a prompt describing what mode the
   application is in.  However, "power users" often barge through the
   prompt.

   User Interfaces MUST NOT provide a subscriber with digits that were
   detected prior to the authentication and authorization of that
   subscriber.  Without prohibition, a subscriber might be able to gain
   access to calling card or other information that predated the
   subscriber's participation in the call.  Note that this prohibition
   MUST be applied on a per-subscription basis.

   KPML provides a <flush> tag in the <pattern> element.  The default is
   not to flush User Input.  Flushing User Input has the effect of
   ignoring key presses entered before the installation of the KPML
   subscription.  To flush User Input, include the tag



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RFC 4730                          KPML                     November 2006


   <flush>yes</flush> in the KPML subscription document.  Note that this
   directive affects only the current subscription dialog/id
   combination.

   Lock-step processing of User Input is where the User Interface issues
   a notification, the Application processes the notification while the
   User Interface buffers additional User Input, the Application
   requests more User Input, and only then does the User Interface
   notify the Application based on the collected User Input.  To direct
   the User Interface to operate in lock-step mode, set the <pattern>
   attribute persist="single-notify".

   The User Interface MUST be able to process <flush>no</flush>.  This
   directive is effectively a no-op.

   Other string values for <flush> may be defined in the future.  If the
   User Interface receives a string it does not understand, it MUST
   treat the string as a no-op.

   If the user presses a key that cannot match any pattern within a
   <regex> tag, the User Interface MUST discard all buffered key presses
   up to and including the current key press from consideration against
   the current or future KPML documents on a given dialog.  However, as
   described above, once there is a match, the User Interface buffers
   any key presses the user entered subsequent to the match.

      NOTE: This behavior allows applications to receive only User Input
      that is of interest to them.  For example, a pre-paid application
      only wishes to monitor for a long pound.  If the user enters other
      stimulus, presumably for other applications, the pre-paid
      application does not want notification of that User Input.  This
      feature is fundamentally different than the behavior of Time
      Division Multiplexer (TDM)-based equipment where every application
      receives every key press.

   To limit reports to only complete matches, set the "nopartial"
   attribute to the <pattern> tag to "true".  In this case, the User
   Interface attempts to match a rolling window over the collected User
   input.

   KPML subscriptions are independent.  Thus, it is not possible for the
   current document to know if a following document will enable barging
   or want User Input flushed.  Therefore, the User Interface MUST
   buffer all User Input, subject to the forced_flush caveat described
   below.






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   On a given SUBSCRIBE dialog with a given id, the User Interface MUST
   buffer all User Input detected between the time of the report and the
   receipt of the next document, if any.  If the next document indicates
   a buffer flush, then the interpreter MUST flush all collected User
   Input from consideration from KPML documents received on that dialog
   with the given event id.  If the next document does not indicate
   flushing the buffered User Input, then the interpreter MUST apply the
   collected User Input (if possible) against the digit maps presented
   by the script's <regex> tags.  If there is a match, the interpreter
   MUST follow the procedures in Section 5.3.  If there is no match, the
   interpreter MUST flush all of the collected User Input.

   Given the potential for needing an infinite buffer for User Input,
   the User Interface MAY discard the oldest User Input from the buffer.
   If the User Interface discards digits, when the User Interface issues
   a KPML notification, it MUST set the forced_flush attribute of the
   <response> tag to "true".  For future use, the Application MUST
   consider any non-null value, other than "false", that it does not
   understand to be the same as "true".

      NOTE: The requirement to buffer all User Input for the entire
      length of the session is not onerous under normal operation.  For
      example, if one has a gateway with 8,000 sessions, and the gateway
      buffers 50 key presses on each session, the requirement is only
      400,000 bytes, assuming one byte per key press.

   Unless there is a suppress indicator in the digit map, it is not
   possible to know if the User Input is for local KPML processing or
   for other recipients of the media stream.  Thus, in the absence of a
   suppression indicator, the User Interface transmits the User Input to
   the far end in real time, using either RFC 2833, generating the
   appropriate tones, or both.

3.6.  DRegex

3.6.1.  Overview

   This subsection is informative in nature.

   The Digit REGular EXpression (DRegex) syntax is a telephony-oriented
   mapping of POSIX Extended Regular Expressions (ERE) [13].

   KPML does not use full POSIX ERE for the following reasons.

   o  KPML will often run on high density or extremely low power and
      memory footprint devices.





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RFC 4730                          KPML                     November 2006


   o  Telephony application convention uses the star symbol ("*") for
      the star key and "x" for any digit 0-9.  Requiring the developer
      to escape the star ("\*") and expand the "x" ("[0-9]") is error
      prone.  This also leads DRegex to use the dot (".") to indicate
      repetition, which was the function of the unadorned star in POSIX
      ERE.

   o  Implementation experience with MGCP [11] and H.248.1 [12] has been
      that implementers and users have a hard time understanding the
      precedence of the alternation operator ("|").  This is due both to
      an under-specification of the operator in those documents and
      conceptual problems for users.  Thus, the SIPPING Working Group
      concluded that DRegex should not support alternation.  That said,
      each KPML <pattern> element may contain multiple regular
      expressions (<regex> elements).  Thus, it is straightforward to
      have pattern alternatives (use multiple <regex> elements) without
      the problems associated with the alternation operator ("|").
      Thus, DRegex does not support the POSIX alternation operator.

   o  DRegex includes character classes (characters enclosed in square
      brackets).  However, the negation operator inside a character
      class only operates on numbers.  That is, a negation class
      implicitly includes A-D, *, and #.  Including A-D, *, and # in a
      negation operator is a no-op.  Those familiar with POSIX would
      expect negation of the digits 4 and 5 (e.g., "[^45]") to include
      all other characters (including A-D, R, *, and #), while those
      familiar with telephony digit maps would expect negation to
      implicitly exclude non-digit characters.  Since the complete
      character set of DRegex is very small, constructing a negation
      class using A-D, R, *, and # requires the user to specify the
      positive inverse mapping.  For example, to specify all key
      presses, including A-D and *, except #, the specification would be
      "[0-9A-D*]" instead of "[^#R]".

   The following table shows the mapping from DRegex to POSIX ERE.

                          +--------+-----------+
                          | DRegex | POSIX ERE |
                          +--------+-----------+
                          | *      | \*        |
                          | .      | *         |
                          | x      | [0-9]     |
                          | [xc]   | [0-9c]    |
                          +--------+-----------+

                   Table 1: DRegex to POSIX ERE Mapping





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RFC 4730                          KPML                     November 2006


   The first substitution, which replaces a star for an escaped star, is
   because telephony application designers are used to using the star
   for the (very common) star key.  Requiring an escape sequence for
   this common pattern would be error prone.  In addition, the usage
   found in DRegex is the same as found in MGCP [11] and H.248.1 [12].

   Likewise, the use of the dot instead of star is common usage from
   MGCP and H.248.1, and reusing the star in this context would also be
   confusing and error prone.

   The "x" character is a common indicator of the digits 0 through 9.
   We use it here, continuing the convention.  Clearly, for the case
   "[xc]", where c is any character, the substitution is not a blind
   replacement of "[0-9]" for "x", as that would result in "[[0-9]c]",
   which is not a legal POSIX ERE.  Rather, the substitution for "[xc]"
   is "[0-9c]".

      NOTE: "x" does not include the characters *, #, R, or A through D.

   Users need to take care not to confuse the DRegex syntax with POSIX
   EREs.  They are NOT identical.  In particular, there are many
   features of POSIX EREs that DRegex does not support.

   As an implementation note, if one makes the substitutions described
   in the above table, then a standard POSIX ERE engine can parse the
   digit string.  However, the mapping does not work in the reverse
   (POSIX ERE to DRegex) direction.  DRegex only implements the
   normative behavior described below.

3.6.2.  Operation

   White space is removed before parsing DRegex.  This enables sensible
   pretty printing in XML without affecting the meaning of the DRegex
   string.

   The following rules demonstrate the use of DRegex in KPML.















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RFC 4730                          KPML                     November 2006


   +---------+---------------------------------------------------------+
   | Entity  | Matches                                                 |
   +---------+---------------------------------------------------------+
   | c       | digits 0-9, *, #, R, and A-D (case insensitive)         |
   | *       | the * character                                         |
   | #       | the # character                                         |
   | R       | The R (Register Recall) key                             |
   | [c]     | Any character in selector                               |
   | [^d]    | Any digit (0-9) not in selector                         |
   | [r1-r2] | Any character in range from r1 to r2, inclusive         |
   | x       | Any digit 0-9                                           |
   | {m}     | m repetitions of previous pattern                       |
   | {m,}    | m or more repetitions of previous pattern               |
   | {,n}    | At most n (including zero) repetitions of previous      |
   |         | pattern                                                 |
   | {m,n}   | At least m and at most n repetitions of previous        |
   |         | pattern                                                 |
   | Lc      | Match the character c if it is "long"; c is a digit 0-9 |
   |         | and A-D, #, or *.                                       |
   +---------+---------------------------------------------------------+

                              DRegex Entities

   For ranges, the A-D characters are disjoint from the 0-9 characters.
   If the device does not have an "R" key, the device MAY report a hook
   flash as an R character.

       +--------------+--------------------------------------------+
       | Example      | Description                                |
       +--------------+--------------------------------------------+
       | 1            | Matches the digit 1                        |
       | [179]        | Matches 1, 7, or 9                         |
       | [2-9]        | Matches 2, 3, 4, 5, 6, 7, 8, 9             |
       | [^15]        | Matches 0, 2, 3, 4, 6, 7, 8, 9             |
       | [02-46-9A-D] | Matches 0, 2, 3, 4, 6, 7, 8, 9, A, B, C, D |
       | x            | Matches 0, 1, 2, 3, 4, 5, 6, 7, 8, 9       |
       | *6[179#]     | Matches *61, *67, *69, or *6#              |
       | x{10}        | Ten digits (0-9)                           |
       | 011x{7,15}   | 011 followed by seven to fifteen digits    |
       | L*           | Long star                                  |
       +--------------+--------------------------------------------+

                              DRegex Examples








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RFC 4730                          KPML                     November 2006


3.7.  Monitoring Direction

   SIP identifies dialogs by their dialog identifier.  The dialog
   identifier is the remote-tag, local-tag, and Call-ID entities defined
   in RFC 3261 [4].

   One method of determining the dialog identifier, particularly for
   third-party applications, is the SIP Dialog Package [17].

   For most situations, such as a monaural point-to-point call with a
   single codec, the stream to monitor is obvious.  In such situations
   the Application need not specify which stream to monitor.

   But there may be ambiguity in specifying only the SIP dialog to
   monitor.  The dialog may specify multiple SDP streams that could
   carry key press events.  For example, a dialog may have multiple
   audio streams.  Wherever possible, the User Interface MAY apply local
   policy to disambiguate which stream or streams to monitor.  In order
   to have an extensible mechanism for identifying streams, the
   mechanism for specifying streams is as an element content to the
   <stream> tag.  The only content defined today is the
   <stream>reverse</stream> tag.

   By default, the User Interface monitors key presses emanating from
   the User Interface.  Given a dialog identifier of Call-ID, local-tag,
   and remote-tag, the User Interface monitors the key presses
   associated with the local-tag.

   In the media proxy case, and potentially other cases, there is a need
   to monitor the key presses arriving from the remote user agent.  The
   optional <stream> element to the <request> tag specifies which stream
   to monitor.  The only legal value is "reverse", which means to
   monitor the stream associated with the remote-tag.  The User
   Interface MUST ignore other values.

      NOTE: The reason this is a tag is so individual stream selection,
      if needed, can be addressed in a backwards-compatible way.
      Further specification of the stream to monitor is the subject of
      future standardization.

3.8.  Multiple Simultaneous Subscriptions

   An Application MAY register multiple User Input patterns in a single
   KPML subscription.  If the User Interface supports multiple,
   simultaneous KPML subscriptions, the Application installs the
   subscriptions either in a new SUBSCRIBE-initiated dialog or on an
   existing SUBSCRIBE-initiated dialog with a new event id tag.  If the
   User Interface does not support multiple, simultaneous KPML



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   subscriptions, the User Interface MUST respond with an appropriate
   KPML status code.

   Some User Interfaces may support multiple key press event
   notification subscriptions at the same time.  In this situation, the
   User Interface honors each subscription individually and
   independently.

   A SIP user agent may request multiple subscriptions on the same
   SUBSCRIBE dialog, using the id parameter to the kpml event request.

   One or more SIP user agents may request independent subscriptions on
   different SIP dialogs, although reusing the same dialog for multiple
   subscriptions is NOT RECOMMENDED.

   If the User Interface does not support multiple, simultaneous
   subscriptions, the User Interface MUST return a KPML document with
   the KPML status code set to 533 on the dialog that requested the
   second subscription.  The User Interface MUST NOT modify the state of
   the first subscription on account of the second subscription attempt.

4.  Event Package Formal Definition

4.1.  Event Package Name

   This document defines a SIP Event Package as defined in RFC 3265 [5].
   The event-package token name for this package is:

           "kpml"

4.2.  Event Package Parameters

   This package defines three Event Package parameters: call-id, remote-
   tag, and local-tag.  These parameters MUST be present, to identify
   the subscription dialog.  The User Interface matches the local-tag
   against the to tag, the remote-tag against the from tag, and the
   call-id against the Call-ID.

   The ABNF for these parameters is below.  It refers to many
   constructions from the ABNF of RFC 3261, such as EQUAL, DQUOTE, and
   token.

   call-id     =  "call-id" EQUAL ( token / DQUOTE callid DQUOTE )
                    ;; NOTE: any DQUOTEs inside callid MUST be escaped!
   remote-tag  =  "remote-tag" EQUAL token
   local-tag   =  "local-tag" EQUAL token





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   If any call-ids contain embedded double-quotes, those double-quotes
   MUST be escaped using the backslash-quoting mechanism.  Note that the
   call-id parameter may need to be expressed as a quoted string.  This
   is because the ABNF for the callid production and the word
   production, which is used by callid (both from RFC 3261 [1]), allow
   some characters (such as "@", "[", and ":") that are not allowed
   within a token.

4.3.  SUBSCRIBE Bodies

   Applications using this event package include an application/
   kpml-request+xml body in SUBSCRIBE requests to indicate which digit
   patterns they are interested in.  The syntax of this body type is
   formally described in Section 5.2.

4.4.  Subscription Duration

   The subscription lifetime should be longer than the expected call
   time.  Subscriptions to this event package MAY range from minutes to
   weeks.  Subscriptions in hours or days are more typical and are
   RECOMMENDED.  The default subscription duration for this event
   package is 7200 seconds.

      Subscribers MUST be able to handle the User Interface returning an
      Expires value smaller than the requested value.  Per RFC 3265 [5],
      the subscription duration is the value returned by the Notifier in
      the 200 OK Expires header.

4.5.  NOTIFY Bodies

   NOTIFY requests can contain application/kpml-response+xml (KPML
   Response) bodies.  The syntax of this body type is formally described
   in Section 5.3.  NOTIFY requests in immediate response to a SUBSCRIBE
   request MUST NOT contain a body unless they are notifying the
   subscriber of an error condition or previously buffered digits.

   Notifiers MAY send notifications with any format acceptable to the
   subscriber (based on the subscriber's inclusion of these formats in
   an Accept header).  A future extension MAY define other NOTIFY
   bodies.  If no "Accept" header is present in the SUBSCRIBE, the body
   type defined in this document MUST be assumed.

4.6.  Subscriber Generation of SUBSCRIBE Requests

   A kpml request document contains a <pattern> element with a series of
   <regex> tags.  Each <regex> element specifies a potential pattern for
   the User Interface to match.  Section 5.1 describes the DRegex, or
   digit regular expression, language.



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   KPML specifies key press event notification filters.  The MIME type
   for KPML requests is application/kpml-request+xml.

   The KPML request document MUST be well formed and SHOULD be valid.
   KPML documents MUST conform to XML 1.0 [14] and MUST use UTF-8
   encoding.

   Because of the potentially sensitive nature of the information
   reported by KPML, subscribers SHOULD use sips: and MAY use S/MIME on
   the content.

   Subscribers MUST be prepared for the notifier to insist on
   authentication of the subscription request.  Subscribers MUST be
   prepared for the notifier to insist on using a secure communication
   channel.

4.7.  Notifier Processing of SUBSCRIBE Requests

   The user information transported by KPML is potentially sensitive.
   For example, it could include calling card or credit card numbers.
   Thus the User Interface (notifier) MUST authenticate the requesting
   party in some way before accepting the subscription.

   User Interfaces MUST implement SIP Digest authentication as required
   by RFC 3261 [4] and MUST implement the sips: scheme and TLS.

   Upon authenticating the requesting party, the User Interface
   determines if the requesting party has authorization to monitor the
   user's key presses.  The default authorization policy is to allow a
   KPML subscriber who can authenticate with a specific identity to
   monitor key presses from SIP sessions in which the same or equivalent
   authenticated identity is a participant.  In addition, KPML will
   often be used, for example, between "application servers"
   (subscribers) and PSTN gateways (notifiers) operated by the same
   domain or federation of domains.  In this situation a notifier MAY be
   configured with a list of subscribers which are specifically trusted
   and authorized to subscribe to key press information related to all
   sessions in a particular context.

   The User Interface returns a Contact URI that may have GRUU [9]
   properties in the Contact header of a SIP INVITE, 1xx, or 2xx
   response.

   After authorizing the request, the User Interface checks to see if
   the request is to terminate a subscription.  If the request will
   terminate the subscription, the User Interface does the appropriate
   processing, including the procedures described in Section 5.2.




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   If the request has no KPML body, then any KPML document running on
   that dialog and addressed by the event id, if present, immediately
   terminates.  This is a mechanism for unloading a KPML document while
   keeping the SUBSCRIBE-initiated dialog active.  This can be important
   for secure sessions that have high costs for session establishment.
   The User Interface follows the procedures described in Section 5.2.

   If the dialog referenced by the kpml subscription does not exist, the
   User Interface follows the procedures in Section 5.3.  Note the User
   Interface MUST issue a 200 OK to the SUBSCRIBE request before issuing
   the NOTIFY, as the SUBSCRIBE itself is well formed.

   If the request has a KPML body, the User Interface parses the KPML
   document.  The User Interface SHOULD validate the XML document
   against the schema presented in Section 5.2.  If the document is not
   valid, the User Interface rejects the SUBSCRIBE request with an
   appropriate error response and terminates the subscription.  If there
   is a loaded KPML document on the subscription, the User Interface
   unloads the document.

   In addition, if there is a loaded KPML document on the subscription,
   the end device unloads the document.

   Following the semantics of SUBSCRIBE, if the User Interface receives
   a resubscription, the User Interface MUST terminate the existing KPML
   request and replace it with the new request.

   It is possible for the INVITE usage of the dialog to terminate during
   key press collection.  The cases enumerated here are explicit
   subscription termination, automatic subscription termination, and
   underlying (INVITE-initiated) dialog termination.

   If a SUBSCRIBE request has an expires of zero (explicit SUBSCRIBE
   termination), includes a KPML document, and there is buffered User
   Input, then the User Interface attempts to process the buffered
   digits against the document.  If there is a match, the User Interface
   MUST generate the appropriate KPML report with the KPML status code
   of 200.  The SIP NOTIFY body terminates the subscription by setting
   the subscription state to "terminated" and a reason of "timeout".

   If the SUBSCRIBE request has an expires of zero and no KPML body or
   the expires timer on the SUBSCRIBE-initiated dialog fires at the User
   Interface (notifier), then the User Interface MUST issue a KPML
   report with the KPML status code 487, Subscription Expired.  The
   report also includes the User Input collected up to the time the
   expires timer expired or when the subscription with expires equal to
   zero was processed.  This could be the null string.




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   Per the mechanisms of RFC 3265 [5], the User Interface MUST terminate
   the SIP SUBSCRIBE dialog.  The User Interface does this via the SIP
   NOTIFY body transporting the final report described in the preceding
   paragraph.  In particular, the subscription state will be
   "terminated" and a reason of "timeout".

   Terminating the subscription when a dialog terminates ensures
   reauthorization (if necessary) for attaching to subsequent
   subscriptions.

   If a SUBSCRIBE request references a dialog that is not present at the
   User Interface, the User Interface MUST generate a KPML report with
   the KPML status code 481, Dialog Not Found.  The User Interface
   terminates the subscription by setting the subscription state to
   "terminated".

   If the KPML document is not valid, the User Interface generates a
   KPML report with the KPML status code 501, Bad Document.  The User
   Interface terminates the subscription by setting the subscription
   state to "terminated".

   If the document is valid but the User Interface does not support a
   namespace in the document, the User Interface MUST respond with a
   KPML status code 502, Namespace Not Supported.

4.8.  Notifier Generation of NOTIFY Requests

   Immediately after a subscription is accepted, the Notifier MUST send
   a NOTIFY with the current location information as appropriate based
   on the identity of the subscriber.  This allows the Subscriber to
   resynchronize its state.

   The User Interface (notifier in SUBSCRIBE/NOTIFY parlance) generates
   NOTIFY requests based on the requirements of RFC 3265 [5].
   Specifically, if a SUBSCRIBE request is valid and authorized, it will
   result in an immediate NOTIFY.

   The KPML payload distinguishes between an initial NOTIFY and a NOTIFY
   informing of key presses.  If there is no User Input buffered at the
   time of the SUBSCRIBE (see below) or the buffered User Input does not
   match the new KPML document, then the immediate NOTIFY MUST NOT
   contain a KPML body.  If User Interface has User Input buffered that
   results in a match using the new KPML document, then the NOTIFY MUST
   return the appropriate KPML document.

   The NOTIFY in response to a SUBSCRIBE request has no KPML if there
   are no matching buffered digits.  An example of this is in Figure 10.




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   If there are buffered digits in the SUBSCRIBE request that match a
   pattern, then the NOTIFY message in response to the SUBSCRIBE request
   MUST include the appropriate KPML document.

   NOTIFY sip:application@example.com SIP/2.0
   Via: SIP/2.0/UDP proxy.example.com
   Max-Forwards: 70
   To: <sip:application@example.com>
   From: <sip:endpoint@example.net>
   Call-Id: 439hu409h4h09903fj0ioij
   Subscription-State: active; expires=7200
   CSeq: 49851 NOTIFY
   Event: kpml

                    Figure 10: Immediate NOTIFY Example

   All subscriptions MUST be authenticated, particularly those that
   match on buffered input.

   KPML specifies the key press notification report format.  The MIME
   type for KPML reports is application/kpml-response+xml.  The default
   MIME type for the kpml event package is application/
   kpml-response+xml.

   If the requestor is not using a secure transport protocol such as TLS
   for every hop (e.g., by using a sips: URI), the User Interface SHOULD
   use S/MIME to protect the user information in responses.

   When the user enters key presses that match a <regex> tag, the User
   Interface will issue a report.

   After reporting, the interpreter terminates the KPML session unless
   the subscription has a persistence indicator.  If the subscription
   does not have a persistence indicator, the User Interface MUST set
   the state of the subscription to "terminated" in the NOTIFY report.

   If the subscription does not have a persistence indicator, to collect
   more digits, the requestor must issue a new request.

      NOTE: This highlights the "one shot" nature of KPML, reflecting
      the balance of features and ease of implementing an interpreter.

   KPML reports have two mandatory attributes, code and text.  These
   attributes describe the state of the KPML interpreter on the User
   Interface.  Note the KPML status code is not necessarily related to
   the SIP result code.  An important example of this is where a legal
   SIP subscription request gets a normal SIP 200 OK followed by a
   NOTIFY, but there is something wrong with the KPML request.  In this



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RFC 4730                          KPML                     November 2006


   case, the NOTIFY would include the KPML status code in the KPML
   report.  Note that from a SIP perspective, the SUBSCRIBE and NOTIFY
   were successful.  Also, if the KPML failure is not recoverable, the
   User Interface will most likely set the Subscription-State to
   "terminated".  This lets the SIP machinery know the subscription is
   no longer active.

   If a pattern matches, the User Interface will emit a KPML report.
   Since this is a success report, the code is "200", and the text is
   "OK".

   The KPML report includes the actual digits matched in the digit
   attribute.  The digit string uses the conventional characters '*' and
   '#' for star and octothorpe, respectively.  The KPML report also
   includes the tag attribute if the regex that matched the digits had a
   tag attribute.

   If the subscription requested digit suppression and the User
   Interface suppressed digits, the suppressed attribute indicates
   "true".  The default value of suppressed is "false".

      NOTE: KPML does not include a timestamp.  There are a number of
      reasons for this.  First, what timestamp would it include?  Would
      it be the time of the first detected key press?  The time the
      interpreter collected the entire string?  A range?  Second, if the
      RTP timestamp is a datum of interest, why not simply get RTP in
      the first place?  That all said, if it is really compelling to
      have the timestamp in the response, it could be an attribute to
      the <response> tag.

   Note that if the monitored (INVITE-initiated) dialog terminates, the
   notifier still MUST explicitly terminate the KPML subscriptions
   monitoring that dialog.

4.9.  Subscriber Processing of NOTIFY Requests

   If there is no KPML body, it means the SUBSCRIBE was successful.
   This establishes the dialog if there is no buffered User Input to
   report.

   If there is a KPML document, and the KPML status code is 200, then a
   match occurred.

   If there is a KPML document, and the KPML status code is between 400
   and 499, then an error occurred with User Input collection.  The most
   likely cause is a timeout condition.





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RFC 4730                          KPML                     November 2006


   If there is a KPML document, and the KPML status code is between 500
   and 599, then an error occurred with the subscription.  See Section 6
   for more on the meaning of KPML status codes.

   The subscriber MUST be mindful of the subscription state.  The User
   Interface may terminate the subscription at any time.

4.10.  Handling of Forked Requests

   Forked requests are NOT ALLOWED for this event type.  This can be
   ensured if the Subscriptions to this event package are sent to SIP
   URIs that have GRUU properties.

4.11.  Rate of Notifications

   The User Interface MUST NOT generate messages faster than 25 messages
   per second, or one message every 40 milliseconds.  This is the
   minimum time period for MF digit spills.  Even 30-millisecond DTMF,
   as one sometimes finds in Japan, has a 20-millisecond off time,
   resulting in a 50-millisecond interdigit time.  This document
   strongly RECOMMENDS AGAINST using KPML for digit-by-digit messaging,
   such as would be the case if the only <regex> is "x".

   The sustained rate of notification shall be no more than 100 Notifies
   per minute.

   The User Interface MUST reliably deliver notifications.  Because
   there is no meaningful metric for throttling requests, the User
   Interface SHOULD send NOTIFY messages over a congestion-controlled
   transport, such as TCP.

      Note that all SIP implementations are already required to
      implement SIP over TCP.

4.12.  State Agents and Lists

   KPML requests are sent to a specific SIP URI, which may have GRUU
   properties, and they attempt to monitor a specific stream that
   corresponds with a specific target dialog.  Consequently,
   implementers MUST NOT define state agents for this event package or
   allow subscriptions for this event package to resource lists using
   the event list extension [18].









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RFC 4730                          KPML                     November 2006


4.13.  Behavior of a Proxy Server

   There are no additional requirements on a SIP Proxy, other than to
   transparently forward the SUBSCRIBE and NOTIFY methods as required in
   SIP.

5.  Formal Syntax

5.1.  DRegex

   The following definition follows RFC 4234 [2].  The definition of
   DIGIT is from RFC 4234, namely, the characters "0" through "9".  Note
   the DRegexCharacter is not a HEXDIG from RFC 4234.  In particular,
   DRegexCharacter includes neither "E" nor "F".  Note that
   DRegexCharacter is case insensitive.

   DRegex           = 1*( DRegexPosition [ RepeatCount ] )
   DRegexPosition   = DRegexSymbol / DRegexSet
   DRegexSymbol     = [ "L" ] DRegexCharacter
   DRegexSet        = "[" 1*DRegexSetList "]"
   DRegexSetList    = DRegexCharacter [ "-" DRegexCharacter ]
   DRegexCharacter  = DIGIT / "A" / "B" / "C" / "D" / "R" / "*" / "#" /
                            "a" / "b" / "c" / "d" / "r"
   RepeatCount      = "." / "{" RepeatRange "}"
   RepeatRange      = Count / ( Count "," Count ) /
                              ( Count "," ) / ( "," Count )
   Count            = 1*DIGIT

                              ABNF for DRegex

   Note that future extensions to this document may introduce other
   characters for DRegexCharacter, in the scheme of H.248.1 [12] or
   possibly as named strings or XML namespaces.


















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RFC 4730                          KPML                     November 2006


5.2.  KPML Request

   The following syntax for KPML requests uses the XML Schema [8].

   <?xml version="1.0" encoding="UTF-8"?>
   <xs:schema targetNamespace="urn:ietf:params:xml:ns:kpml-request"
    xmlns="urn:ietf:params:xml:ns:kpml-request"
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    elementFormDefault="qualified"
    attributeFormDefault="unqualified">
     <xs:element name="kpml-request">
       <xs:annotation>
         <xs:documentation>IETF Keypad Markup Language Request
         </xs:documentation>
       </xs:annotation>
       <xs:complexType>
         <xs:sequence>
           <xs:element name="stream" minOccurs="0">
             <xs:complexType>
               <xs:choice>
                 <xs:element name="reverse" minOccurs="0"/>
                 <xs:any namespace="##other"/>
               </xs:choice>
             </xs:complexType>
           </xs:element>
           <xs:element name="pattern">
             <xs:complexType>
               <xs:sequence>
                 <xs:element name="flush" minOccurs="0">
                   <xs:annotation>
                     <xs:documentation>
                       Default is to not flush buffer
                     </xs:documentation>
                   </xs:annotation>
                   <xs:complexType>
                     <xs:simpleContent>
                       <xs:extension base="xs:string"/>
                     </xs:simpleContent>
                   </xs:complexType>
                 </xs:element>
                 <xs:element name="regex" maxOccurs="unbounded">
                   <xs:annotation>
                     <xs:documentation>
                       Key press notation is a string to allow
                       for future extension of non-16 digit
                       keypads or named keys
                     </xs:documentation>
                   </xs:annotation>



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RFC 4730                          KPML                     November 2006


                   <xs:complexType mixed="true">
                     <xs:choice>
                       <xs:element name="pre" minOccurs="0">
                         <xs:complexType>
                           <xs:simpleContent>
                             <xs:extension base="xs:string"/>
                           </xs:simpleContent>
                         </xs:complexType>
                       </xs:element>
                       <xs:any namespace="##other"/>
                     </xs:choice>
                     <xs:attribute name="tag" type="xs:string"
                                   use="optional"/>
                   </xs:complexType>
                 </xs:element>
               </xs:sequence>
               <xs:attribute name="persist" use="optional">
                 <xs:annotation>
                   <xs:documentation>Default is "one-shot"
                   </xs:documentation>
                 </xs:annotation>
                 <xs:simpleType>
                   <xs:restriction base="xs:string">
                     <xs:enumeration value="one-shot"/>
                     <xs:enumeration value="persist"/>
                     <xs:enumeration value="single-notify"/>
                   </xs:restriction>
                 </xs:simpleType>
               </xs:attribute>
               <xs:attribute name="interdigittimer"
                             type="xs:integer"
                             use="optional">
                 <xs:annotation>
                   <xs:documentation>Default is 4000 (ms)
                   </xs:documentation>
                 </xs:annotation>
               </xs:attribute>
               <xs:attribute name="criticaldigittimer"
                             type="xs:integer"
                             use="optional">
                 <xs:annotation>
                   <xs:documentation>Default is 1000 (ms)
                   </xs:documentation>
                 </xs:annotation>
               </xs:attribute>
               <xs:attribute name="extradigittimer"
                             type="xs:integer"
                             use="optional">



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                 <xs:annotation>
                   <xs:documentation>Default is 500 (ms)
                   </xs:documentation>
                 </xs:annotation>
               </xs:attribute>
               <xs:attribute name="long" type="xs:integer"
                             use="optional"/>
               <xs:attribute name="longrepeat" type="xs:boolean"
                             use="optional"/>
               <xs:attribute name="nopartial" type="xs:boolean"
                             use="optional">
                 <xs:annotation>
                   <xs:documentation>Default is false
                   </xs:documentation>
                 </xs:annotation>
               </xs:attribute>
               <xs:attribute name="enterkey" type="xs:string"
                             use="optional">
                 <xs:annotation>
                   <xs:documentation>No default enterkey
                   </xs:documentation>
                 </xs:annotation>
               </xs:attribute>
             </xs:complexType>
           </xs:element>
         </xs:sequence>
         <xs:attribute name="version" type="xs:string"
                       use="required"/>
       </xs:complexType>
     </xs:element>
   </xs:schema>

                  Figure 12: XML Schema for KPML Requests


















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RFC 4730                          KPML                     November 2006


5.3.  KPML Response

   The following syntax for KPML responses uses the XML Schema [8].

   <?xml version="1.0" encoding="UTF-8"?>
   <xs:schema targetNamespace="urn:ietf:params:xml:ns:kpml-response"
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    xmlns="urn:ietf:params:xml:ns:kpml-response"
    elementFormDefault="qualified"
    attributeFormDefault="unqualified">
     <xs:element name="kpml-response">
       <xs:annotation>
         <xs:documentation>IETF Keypad Markup Language Response
         </xs:documentation>
       </xs:annotation>
       <xs:complexType>
         <xs:attribute name="version" type="xs:string"
                       use="required"/>
         <xs:attribute name="code" type="xs:string"
                       use="required"/>
         <xs:attribute name="text" type="xs:string"
                       use="required"/>
         <xs:attribute name="suppressed" type="xs:boolean"
                       use="optional"/>
         <xs:attribute name="forced_flush" type="xs:string"
                       use="optional">
           <xs:annotation>
             <xs:documentation>
               String for future use for e.g., number of digits lost.
             </xs:documentation>
           </xs:annotation>
         </xs:attribute>
         <xs:attribute name="digits" type="xs:string"
                       use="optional"/>
         <xs:attribute name="tag" type="xs:string" use="optional">
           <xs:annotation>
             <xs:documentation>Matches tag from regex in request
             </xs:documentation>
           </xs:annotation>
         </xs:attribute>
       </xs:complexType>
     </xs:element>
   </xs:schema>

                       XML Schema for KPML Responses






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RFC 4730                          KPML                     November 2006


6.  Enumeration of KPML Status Codes

   KPML status codes broadly follow their SIP counterparts.  Codes that
   start with a 2 indicate success.  Codes that start with a 4 indicate
   failure.  Codes that start with a 5 indicate a server failure,
   usually a failure to interpret the document or to support a requested
   feature.

   KPML clients MUST be able to handle arbitrary status codes by
   examining the first digit only.

   Any text can be in a KPML report document.  KPML clients MUST NOT
   interpret the text field.

        +------+--------------------------------------------------+
        | Code | Text                                             |
        +------+--------------------------------------------------+
        | 200  | Success                                          |
        | 402  | User Terminated without Match                    |
        | 423  | Timer Expired                                    |
        | 481  | Dialog Not Found                                 |
        | 487  | Subscription Expired                             |
        | 501  | Bad Document                                     |
        | 502  | Namespace Not Supported                          |
        | 531  | Persistent Subscriptions Not Supported           |
        | 532  | Multiple Regular Expressions Not Supported       |
        | 533  | Multiple Subscriptions on a Dialog Not Supported |
        | 534  | Too Many Regular Expressions                     |
        +------+--------------------------------------------------+

                        Table 4: KPML Status Codes

7.  IANA Considerations

   This document registers a new SIP Event Package, two new MIME types,
   and two new XML namespaces.

7.1.  SIP Event Package Registration

   Package name:  kpml
   Type:  package
   Contact:  Eric Burger, <e.burger@ieee.org>
   Change Controller:  SIPPING Working Group delegated from the IESG
   Published Specification:  RFC 4730







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7.2.  MIME Media Type application/kpml-request+xml

   MIME media type name:  application
   MIME subtype name:  kpml-request+xml
   Required parameters:  none
   Optional parameters:  Same as charset parameter application/xml as
      specified in XML Media Types [3]
   Encoding considerations:  See RFC 3023 [3].
   Security considerations:  See Section 10 of RFC 3023 [3] and
      Section 8 of RFC 4730
   Interoperability considerations:  See RFC 2023 [3] and RFC 4730
   Published specification:  RFC 4730
   Applications which use this media type:  Session-oriented
      applications that have primitive User Interfaces.
   Change controller:  SIPPING Working Group delegated from the IESG
   Personal and email address for further information:  Eric Burger
      <e.burger@ieee.org>
   Intended usage:  COMMON

7.3.  MIME Media Type application/kpml-response+xml

   MIME media type name:  application
   MIME subtype name:  kpml-response+xml
   Required parameters:  none
   Optional parameters:  Same as charset parameter application/xml as
      specified in XML Media Types [3]
   Encoding considerations:  See RFC 3023 [3].
   Security considerations:  See Section 10 of RFC 3023 [3] and
      Section 8 of RFC 4730
   Interoperability considerations:  See RFC 2023 [3] and RFC 4730
   Published specification:  RFC 4730
   Applications which use this media type:  Session-oriented
      applications that have primitive User Interfaces.
   Change controller:  SIPPING Working Group delegated from the IESG
   Personal and email address for further information:  Eric Burger
      <e.burger@ieee.org>
   Intended usage:  COMMON

7.4.  URN Sub-Namespace Registration for urn:ietf:xml:ns:kpml-request

   URI: urn:ietf:params:xml:ns:kpml-request

   Registrant Contact: The IESG <iesg@ietf.org>








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   XML:

   <?xml version="1.0"?>
   <!DOCTYPE html PUBLIC "-//W3C/DTD XHTML Basic 1.0//EN"
             "http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
   <html xmlns="http://www.w3.org/1999/xhtml">
     <head>
       <meta http-equiv="content-type"
             content="text/html;charset=iso-8859-1"/>
       <title>Key Press Markup Language Request</title>
     </head>
     <body>
       <h1>Namespace for Key Press Markup Language Request</h1>
       <h2>urn:ietf:params:xml:ns:kpml-request</h2>
       <p>
   <a href="ftp://ftp.rfc-editor.org/in-notes/RFC4730.txt">RFC 4730</a>.
       </p>
     </body>
   </html>

7.5.  URN Sub-Namespace Registration for urn:ietf:xml:ns:kpml-response

   URI: urn:ietf:params:xml:ns:kpml-response

   Registrant Contact: The IESG <iesg@ietf.org>

   XML:

   <?xml version="1.0"?>
   <!DOCTYPE html PUBLIC "-//W3C/DTD XHTML Basic 1.0//EN"
             "http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
   <html xmlns="http://www.w3.org/1999/xhtml">
     <head>
       <meta http-equiv="content-type"
             content="text/html;charset=iso-8859-1"/>
       <title>Key Press Markup Language Response</title>
     </head>
     <body>
       <h1>Namespace for Key Press Markup Language Response</h1>
       <h2>urn:ietf:params:xml:ns:kpml-response</h2>
       <p>
   <a href="ftp://ftp.rfc-editor.org/in-notes/rfc4730.txt">RFC 4730</a>.
       </p>
     </body>
   </html>






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RFC 4730                          KPML                     November 2006


7.6.  KPML Request Schema Registration

   Per RFC 3688 [7], IANA registered the XML Schema for KPML as
   referenced in Section 5.2 of RFC 4730.

   URI: urn:ietf:params:xml:schema:kpml-request

   Registrant Contact: <iesg@ietf.org>

7.7.  KPML Response Schema Registration

   Per RFC 3688 [7], IANA registered the XML Schema for KPML as
   referenced in Section 5.3 of RFC 4730.

   URI: urn:ietf:params:xml:schema:kpml-response

   Registrant Contact: IETF, SIPPING Work Group <sipping@ietf.org>, Eric
   Burger <e.burger@ieee.org>.

8.  Security Considerations

   The user information transported by KPML is potentially sensitive.
   For example, it could include calling card or credit card numbers.
   This potentially private information could be provided accidentally
   if the notifier does not properly authenticate or authorize a
   subscription.  Similarly private information (such as a credit card
   number or calling card number) could be revealed to an otherwise
   legitimate subscriber (one operating an IVR) if digits buffered
   earlier in the session are provided unintentionally to the new
   subscriber.

   Likewise, an eavesdropper could view KPML digit information if it is
   not encrypted, or an attacker could inject fraudulent notifications
   unless the messages or the SIP path over which they travel are
   integrity protected.

   Therefore, User Interfaces MUST NOT downgrade their own security
   policy.  That is, if a User Interface policy is to restrict
   notifications to authenticated and authorized subscribers over secure
   communications, then the User Interface must not accept an
   unauthenticated, unauthorized subscription over an insecure
   communication channel.

   As an XML markup, all of the security considerations of RFC 3023 [3]
   and RFC 3406 [6] MUST be met.  Pay particular attention to the
   robustness requirements of parsing XML.





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   Key press information is potentially sensitive.  For example, it can
   represent credit card, calling card, or other personal information.
   Hijacking sessions allow unauthorized entities access to this
   sensitive information.  Therefore, signaling SHOULD be secure, e.g.,
   use of TLS and sips: SHOULD be used.  Moreover, the information
   itself is sensitive so S/MIME or other appropriate mechanisms SHOULD
   be used.

   Subscriptions MUST be authenticated in some manner.  As required by
   the core SIP [4] specification, all SIP implementations MUST support
   digest authentication.  In addition, User Interfaces MUST implement
   support for the sips: scheme and SIP over TLS.  Subscribers MUST
   expect the User Interface to demand the use of an authentication
   scheme.  If the local policy of a User Interface is to use
   authentication or secure communication channels, the User Interface
   MUST reject subscription requests that do not meet that policy.

   User Interfaces MUST begin buffering User Input upon receipt of an
   authenticated and accepted subscription.  This buffering is done on a
   per-subscription basis.

9.  Examples

   This section is informative in nature.  If there is a discrepancy
   between this section and the normative sections above, the normative
   sections take precedence.

9.1.  Monitoring for Octothorpe

   A common need for pre-paid and personal assistant applications is to
   monitor a conversation for a signal indicating a change in user focus
   from the party they called through the application to the application
   itself.  For example, if you call a party using a pre-paid calling
   card, and the party you call redirects you to voice mail, digits you
   press are for the voice mail system.  However, many applications have
   a special key sequence, such as the octothorpe (#, or pound sign) or
   *9, that terminate the called party session and shift the user's
   focus to the application.













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RFC 4730                          KPML                     November 2006


   Figure 16 shows the KPML for long octothorpe.

   <?xml version="1.0"?>
   <kpml-request xmlns="urn:ietf:params:xml:ns:kpml-request"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation=
           "urn:ietf:params:xml:ns:kpml-request kpml-request.xsd"
         version="1.0">
     <pattern>
       <regex>L#</regex>
     </pattern>
   </kpml-request>

                    Figure 16: Long Octothorpe Example

   The regex value L indicates the following digit needs to be a long-
   duration key press.

9.2.  Dial String Collection

   In this example, the User Interface collects a dial string.  The
   application uses KPML to quickly determine when the user enters a
   target number.  In addition, KPML indicates what type of number the
   user entered.

   <?xml version="1.0"?>
   <kpml-request xmlns="urn:ietf:params:xml:ns:kpml-request"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation=
           "urn:ietf:params:xml:ns:kpml-request kpml-request.xsd"
         version="1.0">
     <pattern>
       <regex tag="local-operator">0</regex>
       <regex tag="ld-operator">00</regex>
       <regex tag="vpn">7[x][x][x]</regex>
       <regex tag="local-number7">9xxxxxxx</regex>
       <regex tag="RI-number">9401xxxxxxx</regex>
       <regex tag="local-number10">9xxxxxxxxxx</regex>
       <regex tag="ddd">91xxxxxxxxxx</regex>
       <regex tag="iddd">011x.</regex>
     </pattern>
   </kpml-request>

                 Figure 17: Dial String KPML Example Code

   Note the use of the "tag" attribute to indicate which regex matched
   the dialed string.  The interesting case here is if the user entered
   "94015551212".  This string matches both the "9401xxxxxxx" and



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RFC 4730                          KPML                     November 2006


   "9xxxxxxxxxx" regular expressions.  Both expressions are the same
   length.  Thus the KPML interpreter will pick the "9401xxxxxxx"
   string, as it occurs first in document order.  Figure 18 shows the
   response.

   <?xml version="1.0"?>
   <kpml-response xmlns="urn:ietf:params:xml:ns:kpml-resposne"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation=
           "urn:ietf:params:xml:ns:kpml-response kpml-response.xsd"
         version="1.0"
         code="200" text="OK"
         digits="94015551212" tag="RI-number"/>

                   Figure 18: Dial String KPML Response

10.  Call Flow Examples

10.1.  Supplemental Digits

   This section gives a non-normative example of an application that
   collects supplemental digits.  Supplemental digit collection is where
   the network requests additional digits after the caller enters the
   destination address.  A typical supplemental dial string is four
   digits in length.


























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RFC 4730                          KPML                     November 2006


   Ingress Gateway      Application Server       Egress Gateway
          |                      |                      |
          |                      |                      |
          |                      |                      |
          |(1) INVITE            |                      |
          |-------------------------------------------->|
          |                      |                      |
          |                      |                      |
          |(2) 200 OK            |                      |
          |<--------------------------------------------|
          |                      |                      |
          |                      |                      |
          |(3) ACK               |                      |
          |-------------------------------------------->|
          |                      |                      |
          |                      |                      |
          |(4) SUBSCRIBE (one-shot)                     |
          |<---------------------|                      |
          |                      |                      |
          |                      |                      |
          |(5) 200 OK            |                      |
          |--------------------->|                      |
          |                      |                      |
          |                      |                      |
          |(6) NOTIFY            |                      |
          |--------------------->|                      |
          |                      |                      |
          |                      |                      |
          |(7) 200 OK            |                      |
          |<---------------------|                      |
          |                      |                      |
          |                      |                      |
          |(8)                   |                      |
          |......................|                      |
          |                      |                      |
          |                      |                      |
          |(9) NOTIFY (digits)   |                      |
          |--------------------->|                      |
          |                      |                      |
          |                      |                      |
          |(10) 200 OK           |                      |
          |<---------------------|                      |
          |                      |                      |
          |                      |                      |
          |                      |                      |
          |                      |                      |

                 Figure 19: Supplemental Digits Call Flow



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RFC 4730                          KPML                     November 2006


   In messages (1-3), the ingress gateway establishes a dialog with an
   egress gateway.  The application learns the dialog ID through out-of-
   band mechanisms, such as the Dialog Package or being co-resident with
   the egress gateway.  Part of the ACK message is below, to illustrate
   the dialog identifiers.

   ACK sip:gw@subA.example.com SIP/2.0
   Via: ...
   Max-Forwards: ...
   Route: ...
   From: <sip:phn@example.com>;tag=jfh21
   To: <sip:gw@subA.example.com>;tag=onjwe2
   Call-ID: 12345592@subA.example.com
   ...

   In message (4), the application the requests that gateway collect a
   string of four key presses.

   SUBSCRIBE sip:gw@subA.example.com SIP/2.0
   Via: SIP/2.0/TCP client.subB.example.com;branch=q4i9ufr4ui3
   From: <sip:ap@subB.example.com>;tag=567890
   To: <sip:gw@subA.example.com>
   Call-ID: 12345601@subA.example.com
   CSeq: 1 SUBSCRIBE
   Contact: <sip:ap@client.subB.example.com>
   Max-Forwards: 70
   Event: kpml ;remote-tag="sip:phn@example.com;tag=jfh21"
               ;local-tag="sip:gw@subA.example.com;tag=onjwe2"
               ;call-id="12345592@subA.example.com"
   Expires: 7200
   Accept: application/kpml-response+xml
   Content-Type: application/kpml-request+xml
   Content-Length: 292

   <?xml version="1.0" encoding="UTF-8"?>
   <kpml-request xmlns="urn:ietf:params:xml:ns:kpml-request"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation=
         "urn:ietf:params:xml:ns:kpml-request kpml-request.xsd"
       version="1.0">
     <pattern persist="one-shot">
       <regex>xxxx</regex>
     </pattern>
   </kpml-request>







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   Message (5) is the acknowledgement of the subscription request.

   SIP/2.0 200 OK
   Via: SIP/2.0/TCP subB.example.com;branch=q4i9ufr4ui3;
        received=192.168.125.12
   From: <sip:ap@subB.example.com>;tag=567890
   To: <sip:gw@subA.example.com>;tag=1234567
   Call-ID: 12345601@subA.example.com
   CSeq: 1 SUBSCRIBE
   Contact: <sip:gw27@subA.example.com>
   Expires: 3600
   Event: kpml

   Message (6) is the immediate notification of the subscription.

   NOTIFY sip:ap@client.subB.example.com SIP/2.0
   Via: SIP/2.0/UDP subA.example.com;branch=gw27id4993
   To: <sip:ap@subB.example.com>;tag=567890
   From: <sip:gw@subA.example.com>;tag=1234567
   Call-ID: 12345601@subA.example.com
   CSeq: 1000 NOTIFY
   Contact: <sip:gw27@subA.example.com>
   Event: kpml
   Subscription-State: active;expires=3599
   Max-Forwards: 70
   Content-Length: 0

   Message (7) is the acknowledgement of the notification message.

   SIP/2.0 200 OK
   Via: SIP/2.0/TCP subA.example.com;branch=gw27id4993
   To: <sip:ap@subB.example.com>;tag=567890
   From: <sip:gw@subA.example.com>;tag=1234567
   Call-ID: 12345601@subA.example.com
   CSeq: 1000 NOTIFY

   Some time elapses (8).

   The user enters the input.  The device provides the notification of
   the collected digits in message (9).  Since this was a one-shot
   subscription, note the Subscription-State is "terminated".










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RFC 4730                          KPML                     November 2006


   NOTIFY sip:ap@client.subB.example.com SIP/2.0
   Via: SIP/2.0/UDP subA.example.com;branch=gw27id4993
   To: <sip:ap@subB.example.com>;tag=567890
   From: <sip:gw@subA.example.com>;tag=1234567
   Call-ID: 12345601@subA.example.com
   CSeq: 1001 NOTIFY
   Contact: <sip:gw27@subA.example.com>
   Event: kpml
   Subscription-State: terminated
   Max-Forwards: 70
   Content-Type: application/kpml-response+xml
   Content-Length: 258

   <?xml version="1.0" encoding="UTF-8"?>
   <kpml-response xmlns="urn:ietf:params:xml:ns:kpml-response"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation=
           "urn:ietf:params:xml:ns:kpml-response kpml-response.xsd"
         version="1.0"
         code="200" text="OK"
         digits="4336"/>

   Message (10) is the acknowledgement of the notification.

   SIP/2.0 200 OK
   Via: SIP/2.0/TCP subA.example.com;branch=gw27id4993
   To: <sip:ap@subB.example.com>;tag=567890
   From: <sip:gw@subA.example.com>;tag=1234567
   Call-ID: 12345601@subA.example.com
   CSeq: 1001 NOTIFY





















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RFC 4730                          KPML                     November 2006


10.2.  Multiple Applications

   This section gives a non-normative example of multiple applications.
   One application collects a destination number to call.  That
   application then waits for a "long pound."  During the call, the call
   goes to a personal assistant application, which interacts with the
   user.  In addition, the personal assistant application looks for a
   "short pound."

   For clarity, we do not show the INVITE dialogs.

   Gateway           Card Application      Personal Assistant
      |                      |                      |
      |                      |                      |
      |                      |                      |
      |(1) SUBSCRIBE (persistent)                   |
      |<---------------------|                      |
      |                      |                      |
      |                      |                      |
      |(2) 200 OK            |                      |
      |--------------------->|                      |
      |                      |                      |
      |                      |                      |
      |(3) NOTIFY            |                      |
      |--------------------->|                      |
      |                      |                      |
      |                      |                      |
      |(4) 200 OK            |                      |
      |<---------------------|                      |
      |                      |                      |
      |                      |                      |
      |(5)                   |                      |
      |......................|                      |
      |                      |                      |
      |                      |                      |
      |(6) NOTIFY (tag=card) |                      |
      |--------------------->|                      |
      |                      |                      |
      |                      |                      |
      |(7) 200 OK            |                      |
      |<---------------------|                      |
      |                      |                      |
      |                      |                      |
      |(8)                   |                      |
      |......................|                      |
      |                      |                      |
      |                      |                      |
      |(9) NOTIFY (tag=number)                      |



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RFC 4730                          KPML                     November 2006


      |--------------------->|                      |
      |                      |                      |
      |                      |                      |
      |(10) 200 OK           |                      |
      |<---------------------|                      |
      |                      |                      |
      |                      |                      |
      |(11) SUBSCRIBE        |                      |
      |<--------------------------------------------|
      |                      |                      |
      |                      |                      |
      |(12) 200 OK           |                      |
      |-------------------------------------------->|
      |                      |                      |
      |                      |                      |
      |(13) NOTIFY           |                      |
      |-------------------------------------------->|
      |                      |                      |
      |                      |                      |
      |(14) 200 OK           |                      |
      |<--------------------------------------------|
      |                      |                      |
      |                      |                      |
      |(15)                  |                      |
      |.............................................|
      |                      |                      |
      |                      |                      |
      |(16) NOTIFY (tag=number)                     |
      |-------------------------------------------->|
      |                      |                      |
      |                      |                      |
      |(17) 200 OK           |                      |
      |<--------------------------------------------|
      |                      |                      |
      |                      |                      |
      |(18)                  |                      |
      |.............................................|
      |                      |                      |
      |                      |                      |
      |(19) NOTIFY (tag=#)   |                      |
      |-------------------------------------------->|
      |                      |                      |
      |                      |                      |
      |(20) 200 OK           |                      |
      |<--------------------------------------------|
      |                      |                      |
      |                      |                      |
      |(21)                  |                      |



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RFC 4730                          KPML                     November 2006


      |.............................................|
      |                      |                      |
      |                      |                      |
      |(22) NOTIFY (tag=number)                     |
      |-------------------------------------------->|
      |                      |                      |
      |                      |                      |
      |(23) 200 OK           |                      |
      |<--------------------------------------------|
      |                      |                      |
      |                      |                      |
      |(24)                  |                      |
      |.............................................|
      |                      |                      |
      |                      |                      |
      |(25) NOTIFY (L#)      |                      |
      |--------------------->|                      |
      |                      |                      |
      |                      |                      |
      |(26) 200 OK           |                      |
      |<---------------------|                      |
      |                      |                      |
      |                      |                      |
      |                      |                      |
      |                      |                      |

                 Figure 27: Multiple Application Call Flow

   Message (1) is the subscription request for the card number.

   SUBSCRIBE sip:gw@subA.example.com SIP/2.0
   Via: SIP/2.0/TCP client.subB.example.com;branch=3qo3j0ouq
   From: <sip:ap@subB.example.com>;tag=978675
   To: <sip:gw@subA.example.com>
   Call-ID: 12345601@subA.example.com
   CSeq: 20 SUBSCRIBE
   Contact: <sip:ap@client.subB.example.com>
   Max-Forwards: 70
   Event: kpml ;remote-tag="<sip:phn@example.com;tag=jfi23>"
               ;local-tag="sip:gw@subA.example.com;tag=oi43jfq"
               ;call-id="12345598@subA.example.com"
   Expires: 7200
   Accept: application/kpml-response+xml
   Content-Type: application/kpml-request+xml
   Content-Length: 339






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RFC 4730                          KPML                     November 2006


   <?xml version="1.0" encoding="UTF-8"?>
   <kpml-request xmlns="urn:ietf:params:xml:ns:kpml-request"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation=
           "urn:ietf:params:xml:ns:kpml-request kpml-request.xsd"
         version="1.0">
     <pattern persist="persist">
       <regex tag="card">x{16}</regex>
       <regex tag="number">x{10}</regex>
     </pattern>
   </kpml-request>

   Messages (2-4) are not shown, for brevity.  Message (6) is the
   notification of the card number.

   NOTIFY sip:ap@client.subB.example.com SIP/2.0
   Via: SIP/2.0/UDP subA.example.com;branch=3qo3j0ouq
   To: <sip:ap@subB.example.com>;tag=978675
   From: <sip:gw@subA.example.com>;tag=9783453
   Call-ID: 12345601@subA.example.com
   CSeq: 3001 NOTIFY
   Contact: <sip:gw27@subA.example.com>
   Event: kpml
   Subscription-State: active;expires=3442
   Max-Forwards: 70
   Content-Type: application/kpml-response+xml
   Content-Length: 271

   <?xml version="1.0" encoding="UTF-8"?>
   <kpml-response xmlns="urn:ietf:params:xml:ns:kpml-response"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation=
           "urn:ietf:params:xml:ns:kpml-response kpml-response.xsd"
         version="1.0"
         code="200" text="OK"
         digits="9999888877776666"/>















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RFC 4730                          KPML                     November 2006


   Message (7) is the acknowledgement of the notification.  Time goes by
   in (8).  Message (9) is the notification of the dialed number.

   NOTIFY sip:ap@client.subB.example.com SIP/2.0
   Via: SIP/2.0/UDP subA.example.com;branch=3qo3j0ouq
   To: <sip:ap@subB.example.com>;tag=978675
   From: <sip:gw@subA.example.com>;tag=9783453
   Call-ID: 12345601@subA.example.com
   CSeq: 3001 NOTIFY
   Contact: <sip:gw27@subA.example.com>
   Event: kpml
   Subscription-State: active;expires=3542
   Max-Forwards: 70
   Content-Type: application/kpml-response+xml
   Content-Length: 278

   <?xml version="1.0" encoding="UTF-8"?>
   <kpml-response xmlns="urn:ietf:params:xml:ns:kpml-response"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation=
           "urn:ietf:params:xml:ns:kpml-response kpml-response.xsd"
         version="1.0"
         code="200" text="OK"
         digits="2225551212" tag="number"/>

   Message (11) is the request for long-pound monitoring.

   SUBSCRIBE sip:gw@subA.example.com SIP/2.0
   Via: SIP/2.0/TCP client.subB.example.com;branch=3qo3j0ouq
   From: <sip:ap@subB.example.com>;tag=978675
   To: <sip:gw@subA.example.com>
   Call-ID: 12345601@subA.example.com
   CSeq: 21 SUBSCRIBE
   Contact: <sip:ap@client.subB.example.com>
   Max-Forwards: 70
   Event: kpml ;remote-tag="<sip:phn@example.com;tag=jfi23>"
               ;local-tag="sip:gw@subA.example.com;tag=oi43jfq"
               ;call-id="12345598@subA.example.com"
   Expires: 7200
   Accept: application/kpml-response+xml
   Content-Type: application/kpml-request+xml
   Content-Length: 295









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RFC 4730                          KPML                     November 2006


   <?xml version="1.0" encoding="UTF-8"?>
   <kpml-request xmlns="urn:ietf:params:xml:ns:kpml-request"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation=
           "urn:ietf:params:xml:ns:kpml-request kpml-request.xsd"
         version="1.0">
     <pattern persist="single-notify">
       <regex>L#</regex>
     </pattern>
   </kpml-request>

   Message (13) is the request from the personal assistant application
   for number and pound sign monitoring.

   SUBSCRIBE sip:gw@subA.example.com SIP/2.0
   Via: SIP/2.0/TCP pahost.example.com;branch=xzvsadf
   From: <sip:pa@example.com>;tag=4rgj0f
   To: <sip:gw@subA.example.com>
   Call-ID: 93845@pahost.example.com
   CSeq: 21 SUBSCRIBE
   Contact: <sip:pa12@pahost.example.com>
   Max-Forwards: 70
   Event: kpml ;remote-tag="<sip:phn@example.com;tag=jfi23>"
               ;local-tag="sip:gw@subA.example.com;tag=oi43jfq"
               ;call-id="12345598@subA.example.com"
   Expires: 7200
   Accept: application/kpml-response+xml
   Content-Type: application/kpml-request+xml
   Content-Length: 332

   <?xml version="1.0" encoding="UTF-8"?>
   <kpml-request xmlns="urn:ietf:params:xml:ns:kpml-request"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation=
           "urn:ietf:params:xml:ns:kpml-request kpml-request.xsd"
         version="1.0">
     <pattern persist="persist">
       <regex tag="number">x{10}</regex>
       <regex tag="#">#</regex>
     </pattern>
   </kpml-request>










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RFC 4730                          KPML                     November 2006


   Message (18) is the notification of the number collected.

   NOTIFY sip:pa@example.com SIP/2.0
   Via: SIP/2.0/UDP subA.example.com;branch=xzvsadf
   To: <sip:pa@example.com>;tag=4rgj0f
   From: <sip:gw@subA.example.com>;tag=9788823
   Call-ID: 93845@pahost.example.com
   CSeq: 3021 NOTIFY
   Contact: <sip:gw27@subA.example.com>
   Event: kpml
   Subscription-State: active;expires=3540
   Max-Forwards: 70
   Content-Type: application/kpml-response+xml
   Content-Length: 278

   <?xml version="1.0" encoding="UTF-8"?>
   <kpml-response xmlns="urn:ietf:params:xml:ns:kpml-response"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation=
           "urn:ietf:params:xml:ns:kpml-response kpml-response.xsd"
         version="1.0"
         code="200" text="OK" digits="3335551212" tag="number"/>

   Message (21) is the notification of pound sign detected.

   NOTIFY sip:pa@example.com SIP/2.0
   Via: SIP/2.0/UDP subA.example.com;branch=xzvsadf
   To: <sip:pa@example.com>;tag=4rgj0f
   From: <sip:gw@subA.example.com>;tag=9788823
   Call-ID: 93845@pahost.example.com
   CSeq: 3022 NOTIFY
   Contact: <sip:gw27@subA.example.com>
   Event: kpml
   Subscription-State: active;expires=3540
   Max-Forwards: 70
   Content-Type: application/kpml-response+xml
   Content-Length: 264

   <?xml version="1.0" encoding="UTF-8"?>
   <kpml-response xmlns="urn:ietf:params:xml:ns:kpml-response"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation=
           "urn:ietf:params:xml:ns:kpml-response kpml-response.xsd"
         version="1.0"
         code="200" text="OK"
         digits="#" tag="#"/>





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RFC 4730                          KPML                     November 2006


   Message (27) is the notification of long pound to the card
   application.

   NOTIFY sip:ap@client.subB.example.com SIP/2.0
   Via: SIP/2.0/UDP subA.example.com;branch=3qo3j0ouq
   To: <sip:ap@subB.example.com>;tag=978675
   From: <sip:gw@subA.example.com>;tag=9783453
   Call-ID: 12345601@subA.example.com
   CSeq: 3037 NOTIFY
   Contact: <sip:gw27@subA.example.com>
   Event: kpml
   Subscription-State: active;expires=3216
   Max-Forwards: 70
   Content-Type: application/kpml-response+xml
   Content-Length: 256

   <?xml version="1.0" encoding="UTF-8"?>
   <kpml-response xmlns="urn:ietf:params:xml:ns:kpml-response"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation=
           "urn:ietf:params:xml:ns:kpml-response kpml-response.xsd"
         version="1.0"
         code="200" text="OK"
         digits="#"/>

11.  References

11.1.  Normative References

   [1]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
        Levels", BCP 14, RFC 2119, March 1997.

   [2]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
        Specifications: ABNF", RFC 4234, October 2005.

   [3]  Murata, M., St. Laurent, S., and D. Kohn, "XML Media Types",
        RFC 3023, January 2001.

   [4]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
        Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
        Session Initiation Protocol", RFC 3261, June 2002.

   [5]  Roach, A., "Session Initiation Protocol (SIP)-Specific Event
        Notification", RFC 3265, June 2002.

   [6]  Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
        "Uniform Resource Names (URN) Namespace Definition Mechanisms",
        BCP 66, RFC 3406, October 2002.



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   [7]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
        January 2004.

   [8]  Thompson, H., Beech, D., Maloney, M., and N. Mendelsohn, "XML
        Schema Part 1: Structures", W3C REC REC-xmlschema-1-20010502,
        May 2001.

11.2.  Informative References

   [9]   Rosenberg, J., "Obtaining and Using Globally Routable User
         Agent (UA) URIs (GRUU) in the  Session Initiation Protocol
         (SIP)", Work in Progress, June 2006.

   [10]  Schulzrinne, H. and S. Petrack, "RTP Payload for DTMF Digits,
         Telephony Tones and Telephony Signals", RFC 2833, May 2000.

   [11]  Andreasen, F. and B. Foster, "Media Gateway Control Protocol
         (MGCP) Version 1.0", RFC 3435, January 2003.

   [12]  Groves, C., Pantaleo, M., Anderson, T., and T. Taylor, "Gateway
         Control Protocol Version 1", RFC 3525, June 2003.

   [13]  Institute of Electrical and Electronics Engineers, "Information
         Technology - Portable Operating System Interface (POSIX) - Part
         1: Base Definitions, Chapter 9", IEEE Standard 1003.1,
         June 2001.

   [14]  Bray, T., Paoli, J., Sperberg-McQueen, C., and E. Maler,
         "Extensible Markup Language (XML) 1.0 (Second Edition)", W3C
         REC REC-xml-20001006, October 2000.

   [15]  Rosenberg, J., "A Framework for Application Interaction in the
         Session Initiation Protocol  (SIP)", Work in Progress,
         July 2005.

   [16]  Burger, E., Van Dyke, J., and A. Spitzer, "Media Server Control
         Markup Language (MSCML) and Protocol", RFC 4722, November 2006.

   [17]  Rosenberg, J., Schulzrinne, H., and R. Mahy, "An INVITE-
         Initiated Dialog Event Package for the Session Initiation
         Protocol (SIP)", RFC 4235, November 2005.

   [18]  Roach, A., Campbell, B., and J. Rosenberg, "A Session
         Initiation Protocol (SIP) Event Notification Extension for
         Resource Lists", RFC 4662, August 2006.






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RFC 4730                          KPML                     November 2006


Appendix A.  Contributors

   Ophir Frieder of the Illinois Institute of Technology collaborated on
   the development of the buffer algorithm.

   Jeff Van Dyke worked enough hours and wrote enough text to be
   considered an author under the old rules.

   Robert Fairlie-Cuninghame, Cullen Jennings, Jonathan Rosenberg, and
   we were the members of the Application Stimulus Signaling Design
   Team.  All members of the team contributed to this work.  In
   addition, Jonathan Rosenberg postulated DML in his "A Framework for
   Stimulus Signaling in SIP Using Markup" draft.

   This version of KPML has significant influence from MSCML [16], the
   SnowShore Media Server Control Markup Language.  Jeff Van Dyke and
   Andy Spitzer were the primary contributors to that effort.

   Rohan Mahy did a significant reorganization of the content, as well
   as providing considerable moral support in the production of this
   document.

   That said, any errors, misinterpretation, or fouls in this document
   are our own.

Appendix B.  Acknowledgements

   Hal Purdy and Eric Cheung of AT&T Laboratories helped immensely
   through many conversations and challenges.

   Steve Fisher of AT&T Laboratories suggested the digit suppression
   syntax and provided excellent review of the document.

   Terence Lobo of SnowShore Networks made it all work.

   Jerry Kamitses, Swati Dhuleshia, Shaun Bharrat, Sunil Menon, and
   Bryan Hill helped with clarifying the buffer behavior and DRegex
   syntax.

   Silvano Brewster and Bill Fenner of AT&T Laboratories and Joe Zebarth
   of Nortel helped considerably with making the text clear and DRegex
   tight.

   Bert Culpepper and Allison Mankin gave an early version of this
   document a good scouring.

   Scott Hollenbeck provided XML and MIME review.  Tim Bray pointed out
   the general issue of UTF-8 versus UTF-16 with XML.



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RFC 4730                          KPML                     November 2006


Authors' Addresses

   Eric Burger
   Cantata Technology, Inc.
   18 Keewaydin Dr.
   Salem, NH  03079
   USA

   EMail: eburger@cantata.com


   Martin Dolly
   AT&T Labs

   EMail: mdolly@att.com




































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RFC 4730                          KPML                     November 2006


Full Copyright Statement

   Copyright (C) The IETF Trust (2006).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

   This document and the information contained herein are provided on an
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST,
   AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES,
   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT
   THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY
   IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
   PURPOSE.

Intellectual Property

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
   made any independent effort to identify any such rights.  Information
   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.

   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use of
   such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository at
   http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard.  Please address the information to the IETF at
   ietf-ipr@ietf.org.

Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.






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