SIPREC                                                    A. Hutton, Ed.
Internet-Draft                                        Siemens Enterprise
Intended status:  Informational                           Communications
Expires:  April 5, 2012                                  L. Portman, Ed.
                                                            Nice Systems
                                                                 R. Jain
                                                             IPC Systems
                                                                K. Rehor
                                                     Cisco Systems, Inc.
                                                         October 3, 2011


    An Architecture for Media Recording using the Session Initiation
                                Protocol
                   draft-ietf-siprec-architecture-03

Abstract

   Session recording is a critical requirement in many communications
   environments such as call centers and financial trading.  In some of
   these environments, all calls must be recorded for regulatory,
   compliance, and consumer protection reasons.  Recording of a session
   is typically performed by sending a copy of a media stream to a
   recording device.  This document describes architectures for
   deploying session recording solutions in an environment which is
   based on the Session Initiation Protocol (SIP).

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 5, 2012.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.



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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Definitions  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Session Recording Architecture . . . . . . . . . . . . . . . .  5
     3.1.  Location of the Session Recording Client . . . . . . . . .  5
       3.1.1.  B2BUA acts as a Session Recording Client . . . . . . .  5
       3.1.2.  Endpoint acts as Session Recording Client  . . . . . .  7
       3.1.3.  A SIP Proxy cannot be a Session Recording Client . . .  7
       3.1.4.  Interaction with MEDIACTRL . . . . . . . . . . . . . .  8
       3.1.5.  Interaction with Conference Focus  . . . . . . . . . .  9
     3.2.  Establishing the Recording Session . . . . . . . . . . . . 10
       3.2.1.  Session Recording Client Initiated Recording . . . . . 11
       3.2.2.  Session Recording Server Initiated Recording . . . . . 11
       3.2.3.  Pause/Resume Recording Session . . . . . . . . . . . . 12
       3.2.4.  Media Stream Mixing  . . . . . . . . . . . . . . . . . 12
       3.2.5.  Media Transcoding  . . . . . . . . . . . . . . . . . . 12
     3.3.  Media Recording Metadata . . . . . . . . . . . . . . . . . 12
       3.3.1.  Contents of recording metadata . . . . . . . . . . . . 13
       3.3.2.  Mechanisms for delivery of metadata to Session
               Recording Server . . . . . . . . . . . . . . . . . . . 13
     3.4.  Notifications to the Recorded User Agents  . . . . . . . . 13
     3.5.  Preventing the recording of a SIP session  . . . . . . . . 13
   4.  IANA considerations  . . . . . . . . . . . . . . . . . . . . . 13
   5.  Security considerations  . . . . . . . . . . . . . . . . . . . 13
   6.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
   7.  Informative References . . . . . . . . . . . . . . . . . . . . 14
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15












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1.  Introduction

   Session recording is a critical requirement in many communications
   environments such as call centers and financial trading.  In some of
   these environments, all calls must be recorded for regulatory,
   compliance, and consumer protection reasons.  Recording of a session
   is typically performed by sending a copy of a media stream to a
   recording device.  This document describes architectures for
   deploying session recording solutions in an environment which is
   based on the Session Initiation Protocol (SIP) the requirements for
   which are described in [RFC6341].

   This document focuses on how sessions are established between a
   Session Recording Client (SRC) and the Session Recording Server (SRS)
   for the purpose of conveying the Replicated Media and Media Recording
   Metadata (e.g.  Identity of parties involved) relating to the
   Communication Session.

   Once the Replicated Media and Media Recording Metadata have been
   received by the Session Recording Server they will typically be
   archived for retrieval at a later time.  The procedures relating to
   the archiving and retrieval of this information in outside the scope
   of this document.

   This document only considers active recording, where the Session
   Recording Client purposefully streams media to a Session Recording
   Server.  Passive recording, where a recording device detects media
   directly from the network (E.g. using port mirroring techniques), is
   outside the scope of this document.  In addition, lawful intercept is
   outside the scope of this document which takes account of the IETF
   policy on wiretapping [RFC2804].

   The Recording Session that is established between the Session
   Recording Client and the Session Recording Server uses the normal
   procedures for establishing INVITE initiated dialogs as specified in
   [RFC3261] and uses SDP for describing the media to be used during the
   session as specified in [RFC4566].  However it is intended that some
   extensions to SIP (E.g.  Headers, Option Tags, Etc.) will be defined
   to support the requirements for media recording.  The Replicated
   Media is required to be sent in real-time to the Session Recording
   Server and is not buffered by the Session Recording Client to allow
   for real-time analysis of the media by the Session Recording Server.









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2.  Definitions

   Session Recording Server (SRS):  A Session Recording Server (SRS) is
   a SIP User Agent (UA) that acts as the sink of the recorded media.
   An SRS is a logical function that typically archives media for
   extended durations of time and provides interfaces for search and
   retrieval of the archived media.  An SRS is typically implemented as
   a multi-port device that is capable of receiving media from several
   sources simultaneously.  An SRS is the sink of the recorded session
   metadata.  Note that the term "Server" does not imply the SRS is the
   server side of a signaling protocol as the SRS may be the initiator
   of recording requests.

   Session Recording Client (SRC):  A Session Recording Client (SRC) is
   a SIP User Agent (UA) that acts as the source of the recorded media,
   sending it to the Session Recording Server.  A Session Recording
   Client is a logical function.  Its capabilities may be implemented
   across one or more physical devices.  In practice, a Session
   Recording Client could be a personal device (such as a SIP phone), a
   SIP Media Gateway (MG), a Session Border Controller (SBC), Media
   Server, or an Application Server.  The Session Recording Client is
   also the source of the recorded session metadata.

   Communication Session (CS):  A SIP session created between two or
   more UA's for the purpose of communication which may be recorded.

   Recording Session (RS):  The session created between an Session
   Recording Client and Session Recording Server for the purpose of
   recording a Communication Session.

   Recording aware UA:  A SIP User Agent that is aware of SIP extensions
   associated with the Communication Session.  Such extensions may be
   used to notify the SIP UA that a session is being recorded or to all
   the SIP UA to express preferences as to whether a recording should be
   started, paused, resumed or stopped.

   Media Recording Metadata (MRM):  The metadata describing the
   communication session that is required by the Session Recording
   Server.  This will include for example the identity of users that
   participate in the Communication Session and dialog state.  Typically
   this metadata is archived with the replicated media at the Session
   Recording Server.  The media recording metadata is delivered in real-
   time to the Session Recording Server.

   Replicated Media:  A copy of the media associated with the
   Communication Session created by the Session Recording Client and
   sent to the Session Recording Server.  It may contain all the media
   associated with the communication session (E.g.  Audio and Video) or



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   just a subset (E.g.  Audio).


3.  Session Recording Architecture

3.1.  Location of the Session Recording Client

   This section contains some example session recording architectures
   showing how the Session Recording Client is a logical function that
   can be located in or split between various physical components.

3.1.1.  B2BUA acts as a Session Recording Client

   A SIP B2BUA which has access to the media that is to be recorded may
   act as a Session Recording Client.  The B2BUA may already be aware
   that a session needs to be recorded before the initial establishment
   of the communication session or the decision to record the session
   may occur after the session has been established.

   If the B2BUA/SRC makes the decision to initiate the Recording Session
   (RS) then it will initiate the establishment of a SIP Session by
   sending an INVITE to the Session Recording Server.

   If the Session Recording Server makes the decision to initiate the
   recording session then it will initiate the establishment of a SIP
   Session by sending an INVITE to the B2BUA/Session Recording Client.

   The RS INVITE will need to contain information which identifies the
   session as being established for the purposes of recording and
   prevents the session from being accidently rerouted to a UA which is
   not a SRS.

   The B2BUA/SRC is responsible for notifying the UA's involved in the
   communication session that the session is being recorded.

   The B2BUA/SRC is responsible for honoring any indication from
   recording aware UA's or through some configured policies that the
   communication session must not be recorded.













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                                              +-----------+
                          (Recording Session) |  Session  |
                             +------SIP------>| Recording |
                             |                |  Server   |
                             |  +--RTP/RTCP-->|  (SRS)    |
                             |  |             +-----------+
                             V  |                   ^
                        +-------------+             |
                        |             |             |
                        |             |-- MetaData -+
                        |             |
                        |    B2BUA    |
                        |             |
                        |   Session   |
     +--------+         |  Recording  |         +---------+
     |        |<- SIP ->|   Client    |<- SIP ->|         |
     |  UA-A  |         |   (SRC)     |         |  UA-B   |
     |        |<- RTP ->|             |<- RTP ->|         |
     +--------+         |             |         +---------+
                        +-------------+
     |____________________________________________________|
                    (Communication Session)

          Figure 1: B2BUA Acts as the Session Recording Client.



























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3.1.2.  Endpoint acts as Session Recording Client

   A SIP Endpoint / User Agent may act as a Session Recording Client in
   which case the endpoint sends the Replicated Media to the Session
   Recording Server

   If the endpoint makes the decision to initiate the Recording Session
   then it will initiate the establishment of a SIP Session by sending
   an INVITE to the Session Recording Server.

   If the Session Recording Server makes the decision to initiate the
   Recording Session then it will initiate the establishment of a SIP
   Session by sending an INVITE to the endpoint.



          (Recording Session) +-----------+
         +----------SIP------>|           |
         |  +----RTP/RTCP---->|  Session  |
         |  |                 | Recording |
         |  |                 |  Server   |
         |  | +-- Metadata -->|   (SRS)   |
         |  | |               |           |
         |  | |               +-----------+
         |  | |
         |  | |
         |  | |
         |  | |
         V  | |  (Communication Session)
      +--+------+                     +---------+
      |         |<-------SIP--------->|         |
      |  UA-A   |                     |  UA-B   |
      |  (SRC)  |<-----RTP/RTCP------>|         |
      +---------+                     +---------+


      Figure 2: SIP Endpoint acts as the Session Recording Client



3.1.3.  A SIP Proxy cannot be a Session Recording Client

   A SIP Proxy is unable to act as an SRC because it does not have
   access to the media and therefore has no way of enabling the delivery
   of the replicated media to the SRS






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3.1.4.  Interaction with MEDIACTRL

   The mediactrl architecture [RFC5567] describes an architecure in
   which an application server (AS) controls a Media Server (MS) which
   may be used for purposes such as conferencing and recording media
   streams.  In the [RFC5567] architecure the AS typically uses SIP
   Third Party Call Control (3PCC) to instruct the SIP UA's to direct
   their media to the Media Server.

   The Session Recording Client and Session Recording Server described
   in this document may act as an application server as described in
   [RFC5567] and therefore may when further decomposed be made up of an
   application server which uses a mediactrl interface to control a
   media server for the purpose of recording the media streams however
   this interface is considered outside the scope of this document.

   In addition, any appropriate control protocols such as RTC-Web can be
   used for such decomposition.


                                     Session Recording Server (SRS)
                              +----------------------------------------+
                              |                                        |
          (Recording Session) |  +-----------+          +------------+ |
          +------------SIP----|->|           |          |            | |
          |                   |  | MediaCtrl |MEDIACTRL |   Media    | |
          |                   |  |Application|<-------->|   Server   | |
          |    +-----Metadata--->|  Server   |          |  (Recorder)| |
          |    |              |  |           |          |            | |
          |    |              |  +-----------+          +------------+ |
          |    |              |                              ^         |
          |    |              +------------------------------|---------+
          |    |  +--------------- RTP/RTCP -----------------+
          |    |  |
          V    |  V
        +---+------+                          +---------+
        |          |<-------SIP-------------->|         |
        |   UA-A   | (Communication Session)  |  UA-B   |
        |   (SRC)  |<-------RTP/RTCP--------->|         |
        +----------+                          +---------+

           Figure 3: Example of Session Recording Server using MEDIACTRL









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                                                    +----------+
                 (Recording Session)                | Session  |
           +-----------SIP------------------------->|Recording |
           |                                        |  Server  |
           |                                        |   (SRS)  |
           |  UA-A Session Recording Client (SRC)   +----------+
    +----------------------------------------+         |
    |                                        |         |
    |  +-----------+          +------------+ |         |
    |  |           | Control  |            |<----RTP---+    +---------+
    |  |    UA     | Protocol |   Media    | |              |         |
    |  |Application|<-------->|  Server    | |<----SIP----->|  UA-B   |
    |  |  Server   |          |            |<-----RTP------>|         |
    |  |           |          |            | |              +---------+
    |  +-----------+          +------------+ |
    |                                        |
    +----------------------------------------+
           Figure 4: Example of Session Recording Client decomposition


3.1.5.  Interaction with Conference Focus

   In the case of a centralised conference a combination of the
   conference focus and mixer [RFC4353] may act as a SRC and therefore
   provide the SRS with the replicated media and associated media
   recording metadata.  In this arrangement the SRC is able to provide
   media and metadata relating to each of the participants, including,
   for example, any side conversations where the media passes through
   the mixer

   The conference focus may also act as a Recording Aware UA in the case
   when one of the participants acts as a SRC.

   In an alternative arrangement a SIP endpoint which is a conference
   participant can act as an SRC.  The SRC will in this case have access
   to the media and metadata relating to that particular participant and
   may be able to obtain additional metadata from the conference focus.
   The SRC may for example use the conference event package as described
   in [RFC4575] to obtain information about other participants which it
   provides to the SRS within the media recording metadata.

   The SRC may be involved in the conference from the very beginning or
   may join at some later point of time.








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                                User 1
                            +-----------+
                            |           |
                            |           |
                            |Participant|
                            |     1     |
                            |           |
                            +-----------+
                                  |SIP
                                  |Dialog
                                  |1
       User 2                     |        Recording
    +-----------+           +-----------+  Session     *************
    |           |           |           |--------------*           *
    |           |           |           |----RTP 1 --->*           *
    |Participant|-----------| Focus/SRC |----RTP 2 --->*    SRS    *
    |     2     |  SIP      |           |----RTP 3 --->*           *
    |           |  Dialog   |           |              *           *
    +-----------+  2        +-----------+              *************
                                  |
                                  |SIP
                                  |Dialog
                                  |3
                                  |
                            +-----------+
                            |           |
                            |           |
                            |Participant|
                            |    3      |
                            |           |
                            +-----------+
                               User 3

           Figure 5: Conference Focus acting as an SRC.


3.2.  Establishing the Recording Session

   The Session Recording Client or the Session Recording Server may
   initiate the Recording Session.

   It should be noted that the Recording Session is independent from the
   Communication Session that is being recorded at both the SIP dialog
   level and at the session level.

   Concerning media negotiation, regular SIP/SDP capabilities should be
   used, and existing transcoding capabilities should not be precluded




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3.2.1.  Session Recording Client Initiated Recording

   When the Session Recording Client initiates the Recording Session for
   the purpose of conveying media to the Session Recording Server it
   performs the following actions.

   o  The SRC is provisioned with a URI for the SRS, which is resolved
      through normal [RFC3263] procedures.

   o  Initiates the dialog by sending an INVITE request to the Session
      Recording Server.  The dialog is established according to the
      normal procedures for establishing an INVITE initiated dialog as
      specified in [RFC3261].

   o  Include in the INVITE an indication that the session is
      established for the purpose of recording the associated media.
      Possible mechanisms for this include using the Require header
      and/or a new media feature tag similar to the use of "isfocus" as
      defined in [RFC3840]

   o  If the Replicated Media is to be started immediately then the
      Session Recording Client will include an SDP attribute of
      "a=sendonly" for each media line or "a=inactive" if it is not
      ready to transmit the media.

   o  The Recording Session may replicate all media associated with the
      Communication Session or only a subset.

   o  Replicate the media streams that are to be recorded and transmit
      the media to the Session Recording Server.

3.2.2.  Session Recording Server Initiated Recording

   When the Session Recording Server initiates the media recording
   session with the Session Recording Client it performs the following
   actions.

   o  Send an INVITE request to the Session Recording Client

   o  Include in the INVITE an indication that the session is
      established for the purpose of recording the associated media.
      Possible mechanisms for this include using the Require header or a
      media feature tag similar to the use of "isfocus" as defined in
      [RFC3840]

   o  Identify the session that is to be recorded - Possibly using the
      Join header [RFC3911]




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   o  If the Recording Session is to be started immediately then the
      Session Recording Client will include an SDP attribute of
      "a=recvonly" for each media line or "a=inactive" if it is not
      ready to receive the media

   If the Session Recording Server does not have prior knowledge of what
   media streams are available to be recorded it can make use of an
   offerless INVITE which allows the Session Recording Client to make
   the initial SDP offer.

3.2.3.  Pause/Resume Recording Session

   The Session Recording Server or the Session Recording Client may
   pause the recording by changing the SDP direction attribute to
   "inactive" and resume the recording by changing the direction back to
   "recvonly" or "sendonly".

3.2.4.  Media Stream Mixing

   In a basic session involving only audio there are typically two
   audio/RTP streams between the two UA's involved transporting media in
   each direction.  When recording this media the two streams may be
   mixed at the SRC before being transmitted to the SRS or it may be a
   requirement of the recording server that the media streams are not
   mixed and are sent to the SRS as two separate streams.  The case when
   media is mixed at the SRC is simple as only a single media stream is
   required to be sent to the SRS.  However in the case when the media
   streams are not mixed then the SDP offer sent to the SRS must
   describe two separate media streams.

3.2.5.  Media Transcoding

   The communication session (CS) and the recording session (RS) are
   negotiated separately using a standard SDP offer/answer exchange
   which may result in the SRC having to perform media transcoding
   between the two sessions.  If the SRC is not capable of performing
   media transcoding it may limit the media formats in the offer to the
   SRS depending on what media is negotiated on the CS or may limit what
   it includes in the offer on the CS if it has prior knowledge of the
   media formats supported by the SRS.  However typically the SRS will
   be the more capable device which can provide a wide range of media
   format options to the SRC and may also be able to make use of a media
   transcoder as detailed in [RFC5369].

3.3.  Media Recording Metadata






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3.3.1.  Contents of recording metadata

   The metadata model is defined in [I-D.ietf-siprec-metadata].

3.3.2.  Mechanisms for delivery of metadata to Session Recording Server

   The SRS obtains session recording metadata from the SRC.  The
   metadata is transported via SIP based mechanisms as specified in
   [I-D.ietf-siprec-protocol]

   It is also possible that metadata is transported via non SIP based
   mechanisms but these are considered out of scope.

3.4.  Notifications to the Recorded User Agents

   Typically a user that is involved in a session that is to be recorded
   is notified by an announcement at the beginning of the session or may
   receive some warning tones within the media.  However the
   standardization of media recording protocols when using SIP enable an
   indication that the call is being recorded to be included in the SIP
   requests and responses associated with that communication session.

   It is the Session Recording Client that provides the notification to
   all SIP UA's for which it is replicating received media for the
   purpose of recording including the local user if the Session
   Recording Client is a SIP endpoint.

3.5.  Preventing the recording of a SIP session

   A Recording Aware UA may during the initial session establishment or
   during an established session provide an indication of their
   preference with regard to recording the media in the communication
   session.  The mechanism for this are specified in
   [I-D.ietf-siprec-protocol]


4.  IANA considerations

   None.


5.  Security considerations

   The Recording Session is fundamentally a standard SIP dialog and
   media session and therefore make use of existing SIP security
   mechanisms for securing the Recording Session and Media Recording
   Metadata.




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   The intended use of this architecture is only for the case where the
   users are aware of that they are being recorded and the architecture
   provides the means for the Session Recording Client to notify users
   that they are being recorded.

   This architectural solution is not intended to support lawful
   intercept which in contrast requires that users are not informed.

   It is the responsibility of the Session Recording Server to protect
   the Replicated Media and Media Recording Metadata once it has been
   received and archived.


6.  Acknowledgements

   Thanks to John Elwell, Alan Johnson, Cullen Jennings, Hadriel Kaplan,
   Henry Lum, Paul Kyzivat, Parthasarathi R, Ram Mohan R, and Charles
   Eckel for their significant contributions and assistance with this
   document and Working Group, and to all the members of the SIPREC WG
   mailing list for providing valuable input to this work.


7.  Informative References

   [RFC3261]  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.

   [RFC3263]  Rosenberg, J. and H. Schulzrinne, "Session Initiation
              Protocol (SIP): Locating SIP Servers", RFC 3263,
              June 2002.

   [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
              Description Protocol", RFC 4566, July 2006.

   [RFC3911]  Mahy, R. and D. Petrie, "The Session Initiation Protocol
              (SIP) "Join" Header", RFC 3911, October 2004.

   [RFC6341]  Rehor, K., Portman, L., Hutton, A., and R. Jain, "Use
              Cases and Requirements for SIP-Based Media Recording
              (SIPREC)", RFC 6341, August 2011.

   [I-D.ietf-siprec-metadata]
              R, R., Ravindran, P., and P. Kyzivat, "Session Initiation
              Protocol (SIP) Recording Metadata",
              draft-ietf-siprec-metadata-04 (work in progress),
              September 2011.



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   [I-D.ietf-siprec-protocol]
              Portman, L., Lum, H., Johnston, A., and A. Hutton,
              "Session Recording Protocol",
              draft-ietf-siprec-protocol-00 (work in progress),
              August 2011.

   [RFC3265]  Roach, A., "Session Initiation Protocol (SIP)-Specific
              Event Notification", RFC 3265, June 2002.

   [RFC3840]  Rosenberg, J., Schulzrinne, H., and P. Kyzivat,
              "Indicating User Agent Capabilities in the Session
              Initiation Protocol (SIP)", RFC 3840, August 2004.

   [RFC4353]  Rosenberg, J., "A Framework for Conferencing with the
              Session Initiation Protocol (SIP)", RFC 4353,
              February 2006.

   [RFC4575]  Rosenberg, J., Schulzrinne, H., and O. Levin, "A Session
              Initiation Protocol (SIP) Event Package for Conference
              State", RFC 4575, August 2006.

   [RFC5567]  Melanchuk, T., "An Architectural Framework for Media
              Server Control", RFC 5567, June 2009.

   [RFC5369]  Camarillo, G., "Framework for Transcoding with the Session
              Initiation Protocol (SIP)", RFC 5369, October 2008.

   [RFC2804]  IAB and IESG, "IETF Policy on Wiretapping", RFC 2804,
              May 2000.


Authors' Addresses

   Andrew Hutton (editor)
   Siemens Enterprise Communications
   Hofmannstrasse 51
   Munich D-81379
   Germany

   Email:  andrew.hutton@siemens-enterprise.com











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Internet-Draft      Architecture for Media Recording        October 2011


   Leon Portman (editor)
   Nice Systems
   8 Hapnina
   Ra'anana  43017
   Israel

   Email:  leon.portman@nice.com


   Rajnish Jain
   IPC Systems
   777 Commerce Drive
   Fairfield, CT  06825
   USA

   Email:  rajnish.jain@ipc.com


   Ken Rehor
   Cisco Systems, Inc.
   170 West Tasman Drive
   San Jose, CA  95134-1706
   USA

   Email:  krehor@cisco.com


























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