Use Cases and Requirements for SIP-Based Media Recording (SIPREC)

Internet Engineering Task Force (IETF)                     K. Rehor, Ed.
Request for Comments: 6341                                 Cisco Systems
Category: Informational                                  L. Portman, Ed.
ISSN: 2070-1721                                             NICE Systems
                                                               A. Hutton
                                       Siemens Enterprise Communications
                                                                 R. Jain
                                                             IPC Systems
                                                             August 2011


   Use Cases and Requirements for SIP-Based Media Recording (SIPREC)

Abstract

   Session recording is a critical requirement in many business
   communications environments, such as call centers and financial
   trading floors.  In some of these environments, all calls must be
   recorded for regulatory and compliance reasons.  In others, calls may
   be recorded for quality control or business analytics.

   Recording is typically performed by sending a copy of the session
   media to the recording devices.  This document specifies requirements
   for extensions to SIP that will manage delivery of RTP media to a
   recording device.  This is being referred to as SIP-based Media
   Recording.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6341.

Copyright Notice

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Table of Contents

   1. Introduction ....................................................2
   2. Requirements Notation ...........................................4
   3. Definitions .....................................................4
   4. Use Cases .......................................................5
   5. Requirements ...................................................10
   6. Privacy Considerations .........................................13
   7. Security Considerations ........................................14
   8. Acknowledgements ...............................................15
   9. Normative References ...........................................15

1.  Introduction

   Session recording is a critical operational requirement in many
   businesses, especially where voice is used as a medium for commerce
   and customer support.  A prime example where voice is used for trade
   is the financial industry.  The call recording requirements in this
   industry are quite stringent.  The recorded calls are used for
   dispute resolution and compliance.  Other businesses, such as
   customer support call centers, typically employ call recording for
   quality control or business analytics, with different requirements.

   Depending on the country and its regulatory requirements, financial
   trading floors typically must record all calls.  In contrast, call
   centers typically only record a subset of the calls, and calls must
   not fail, regardless of the availability of the recording device.

   Respecting the privacy rights and wishes of users engaged in a call
   is of paramount importance.  In many jurisdictions, participants have
   a right to know that the session is being recorded or might be
   recorded, and they have a right to opt out, either by terminating the
   call or by demanding that the call not be recorded.  Therefore, this
   document contains requirements for being able to notify users that a
   call is being recorded and for users to be able to request that a
   call not be recorded.  Use cases where users participating in a call
   are not informed that the call is or might be recorded are outside
   the scope of this document.  In particular, lawful intercept is
   outside the scope of this document.

   Furthermore, a one-size-fits-all model will not fit all markets where
   the scale and cost burdens vary widely and where needs differ for
   such solution capabilities as media injection, transcoding, and
   security.  If a standardized solution supports all of the
   requirements from every recording market but doing so would be
   expensive for markets with lesser needs, then proprietary solutions
   for those markets will continue to propagate.  Care must be taken,
   therefore, to make a standards-based solution support optionality and
   flexibility.

   This document specifies requirements for using SIP [RFC3261] between
   a Session Recording Client and a Session Recording Server to control
   the recording of media that has been transmitted in the context of a
   Communication Session.  A Communication Session is the "call" between
   participants.  The Session Recording Client is the source of the
   recorded media.  The Session Recording Server is the sink of recorded
   media.  It should be noted that the requirements for the protocol
   between a Session Recording Server and Session Recording Client have
   very similar requirements (such as codec and transport negotiation,
   encryption key interchange, and firewall traversal) as compared to
   regular SIP media sessions.  The choice of SIP for session recording
   provides reuse of an existing protocol.

   The recorded sessions can be any RTP media sessions, including voice,
   dual-tone multifrequency (DTMF) (as defined by [RFC4733]), video, and
   text (as defined by [RFC4103]).

   An archived session recording is typically comprised of the
   Communication Session media content and the Communication Session
   Metadata.  The Communication Session Metadata allows recording
   archives to be searched and filtered at a later time and allows a
   session to be played back in a meaningful way, e.g., with correct
   synchronization between the media.  The Communication Session
   Metadata needs to be conveyed from the Session Recording Client to
   the Session Recording Server.

   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, is outside the scope of this document.

2.  Requirements Notation

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119] and indicate
   requirement levels for compliant mechanisms.

3.  Definitions

   Session Recording Server (SRS): A Session Recording Server (SRS) is a
      SIP User Agent (UA) that is a specialized media server or
      collector that acts as the sink of the recorded media.  An SRS is
      typically implemented as a multi-port device that is capable of
      receiving media from multiple sources simultaneously.  An SRS is
      the sink of the recorded session metadata.

   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 SRS.  An SRC is a logical function.  Its
      capabilities may be implemented across one or more physical
      devices.  In practice, an SRC could be a personal device (such as
      a SIP phone), a SIP Media Gateway (MG), a Session Border
      Controller (SBC), or a SIP Media Server (MS) integrated with an
      Application Server (AS).  This specification defines the term
      "SRC" such that all such SIP entities can be generically addressed
      under one definition.  The SRC provides metadata to the SRS.

   Communication Session (CS): A session created between two or more SIP
      User Agents (UAs) that is the subject of recording.

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

   Figure 1 pictorially represents the relationship between a Recording
   Session and Communication Session.

     +-------------+                                      +-----------+
     |             |        Communication Session         |           |
     |     A       |<------------------------------------>|     B     |
     |             |                                      |           |
     +-------------+                                      +-----------+
     ..................................................................
     .                             Session                            .
     .                            Recording                           .
     .                             Client                             .
     ..................................................................
                                      |
                                      | Recording
                                      | Session
                                      |
                                      v
                               +------------+
                               |   Session  |
                               |  Recording |
                               |   Server   |
                               +------------+

                                 Figure 1

   Metadata: Information that describes recorded media and the CS to
      which they relate.

   Pause and Resume during a Communication Session:
      Pause: The action of temporarily discontinuing the transmission
      and collection of RS media.
      Resume: The action of recommencing the transmission and collection
      of RS media.

   Most security-related terms in this document are to be understood in
   the sense defined in [RFC4949]; such terms include, but are not
   limited to, "authentication", "confidentiality", "encryption",
   "identity", and "integrity".

4.  Use Cases

   Use Case 1: Full-time Recording: One Recording Session for each
      Communication Session.

      For example, the diagram below shows the life cycle of
      Communication Sessions (CSs) and the relationship to the Recording
      Sessions (RS).

         CS  |--- CS 1 ---|      |--- CS 2 ---|     |--- CS 3 ---|

         RS  |--- RS 1 ---|      |--- RS 2 ---|     |--- RS 3 ---|
         t--->

                                 Figure 2

      Record every CS for each specific extension/person.

      The need to record all calls is typically due to business process
      purposes (such as transaction confirmation or dispute resolution)
      or to ensure compliance with governmental regulations.
      Applications include enterprise, contact center, and financial
      trading floors.

      This is also commonly known as Total Recording.

   Use Case 2: Selective Recording: Start a Recording Session when a
      Communication Session to be recorded is established.

      In this example, Communication Sessions 1 and 3 are recorded but
      CS 2 is not.

         CS  |--- CS 1 ---|      |--- CS 2 ---|     |--- CS 3 ---|

         RS  |--- RS 1----|                         |--- RS 2 ---|
         t--->

                                 Figure 3

   Use Case 3: Start/Stop a Recording Session during a Communication
      Session.

      The Recording Session starts during a Communication Session,
      either manually via a user-controlled mechanism (e.g., a button on
      a user's phone) or automatically via an application (e.g., a
      contact center customer service application) or business event.  A
      Recording Session ends either during the Communication Session or
      when the Communication Session ends.  One or more Recording
      Sessions may record each Communication Session.

         CS  |------------- Communication Session -----------|

         RS           |---- RS 1 ----|  |---- RS 2 -----|
         t--->

                                 Figure 4

   Use Case 4: Persistent Recording: A single Recording Session captures
      one or more Communication Sessions.

                |--- CS 1 ---|      |--- CS 2 ---|     |--- CS 3 ---|

         RS  |------------------- Recording Session ------------------|
         t--->

                                 Figure 5

      A Recording Session records continuously without interruption.
      Periods when there is no CS in progress must be reproduced upon
      playback (e.g., by recording silence during such periods, or by
      not recording such periods but marking them by means of metadata
      for utilization on playback, etc.).  Applications include
      financial trading desks and emergency (first-responder) service
      bureaus.  The length of a Persistent Recording Session is
      independent from the length of the actual Communication Sessions.
      Persistent Recording Sessions avoid issues such as media clipping
      that can occur due to delays in Recording Session establishment.

      The connection and attributes of media in the Recording Session
      are not dynamically signaled for each Communication Session before
      it can be recorded; however, codec re-negotiation is possible.

      In some cases, more than one concurrent Communication Session (on
      a single end-user apparatus, e.g., trading-floor turret) is mixed
      into one Recording Session:

                       |-------- CS 1 -------|
                          |-------- CS 2 -------|
                     |-------- CS 3 -------|

         RS  |----------- Recording Session --------------|
         t--->

                                 Figure 6

   Use Case 5: Real-time Recording Controls.

      For an active Recording Session, privacy or security reasons may
      demand not capturing a specific portion of a conversation.  An
      example is for PCI (payment card industry) compliance where credit
      card information must be protected.  One solution is not to record
      a caller speaking their credit card information.

      An example of a real-time control is Pause/Resume.

   Use Case 6: IVR / Voice Portal Recording.

      Self-service Interactive Voice Response (IVR) applications may
      need to be recorded for application performance tuning or to meet
      compliance requirements.

      Metadata about an IVR session recording must include session
      information and may include application context information (e.g.,
      VoiceXML session variables, dialog names, etc.).

   Use Case 7: Enterprise Mobility Recording.

      Many agents and enterprise workers whose calls are to be recorded
      are not located on company premises.

      Examples:

      o  Home-based agents or enterprise workers.

      o  Mobile phones of knowledge workers (e.g., insurance agents,
         brokers, or physicians) when they conduct work-related (and
         legally required recording) calls.

   Use Case 8: Geographically distributed or centralized recording.

      Enterprises such as banks, insurance agencies, and retail stores
      may have many locations, possibly up to thousands of small sites.
      Frequently, only phones and network infrastructure are installed
      in branches, without local recording services.  In cases where
      calls inside or between branches must be recorded, a centralized
      recording system in data centers together with telephony
      infrastructure (e.g., Private Branch Exchange (PBX)) may be
      deployed.

   Use Case 9: Record complex call scenarios.

      The following is an example of a scenario where one call that is
      recorded must be associated with a related call that also must be
      recorded.

      o  A Customer is in a conversation with a Customer Service Agent.

      o  The Agent puts the Customer on hold in order to consult with a
         Supervisor.

      o  The Agent enters into a conversation with the Supervisor.

      o  The Agent disconnects from the Supervisor, then reconnects with
         the Customer.

      o  The Supervisor call must be associated with the original
         Customer call.

   Use Case 10: High availability and continuous recording.

      Specific deployment scenarios present different requirements for
      system availability, error handling, etc., including the
      following:

      o  An SRS must always be available at call setup time.

      o  No loss of media recording can occur, including during failure
         of an SRS.

      o  The Communication Session must be terminated (or suitable
         notification given to parties) in the event of a recording
         failure.

   Use Case 11: Record multi-channel, multimedia session.

      Some applications require the recording of more than one media
      stream, possibly of different types.  Media are synchronized,
      either at storage or at playback.

      Speech analytics technologies (e.g., word spotting, emotion
      detection, speaker identification) may require speaker-separated
      recordings for optimum performance.

      Multi-modal contact centers may include audio, video, IM, or other
      interaction modalities.

      In trading-floor environments, in order to minimize storage and
      recording system resources, it may be preferable to mix multiple
      concurrent calls (Communication Sessions) on different handsets/
      speakers on the same turret into a single recording session.

   Use Case 12: Real-time media processing.

      It must be possible for an SRS to support real-time media
      processing, such as speech analytics of trading-floor
      interactions.  Real-time analytics may be employed for automatic
      intervention (stopping interaction or alerting) if, for example, a
      trader is not following regulations.

      Speaker separation is required in order to reliably detect who is
      saying specific phrases.

5.  Requirements

   The following are requirements for SIP-based Media Recording:

   o  REQ-001: The mechanism MUST provide a means for using the SIP
      protocol for establishing, maintaining, and terminating Recording
      Sessions between a Session Recording Client and a Session
      Recording Server.

   o  REQ-002: The mechanism MUST support the ability to record all CSs
      in their entirety.

   o  REQ-003: The mechanism MUST support the ability to record selected
      CSs in their entirety, according to policy.

   o  REQ-004: The mechanism MUST support the ability to record selected
      parts of selected CSs.

   o  REQ-005: The mechanism MUST support the ability to record a CS
      without loss of media of RS (for example, clipping media at the
      beginning of the CS) due to RS recording preparation and also
      without impacting the quality or timing of the CS (for example,
      delaying the start of the CS while preparing for a recording
      session).  See Use Case 4 in Section 4 for more details.

   o  REQ-006: The mechanism MUST support the recording of IVR sessions.

   o  REQ-007: The mechanism MUST support the recording of the following
      RTP media types: voice, DTMF (as defined by [RFC4733]), video, and
      text (as defined by [RFC4103]).

   o  REQ-008: The mechanism MUST support the ability for an SRC to
      deliver mixed audio streams from multiple Communication Sessions
      to an SRS.

      Note: A mixed audio stream is where several related Communication
      Sessions are carried in a single Recording Session.  A mixed-media
      stream is typically produced by a mixer function.  The RS MAY be
      informed about the composition of the mixed streams through
      session metadata.

   o  REQ-009: The mechanism MUST support the ability for an SRC to
      deliver mixed audio streams from different parties of a given
      Communication Session to an SRS.

   o  REQ-010: The mechanism MUST support the ability to deliver to the
      SRS multiple media streams for a given CS.

   o  REQ-011: The mechanism MUST support the ability to pause and
      resume the transmission and collection of RS media.

   o  REQ-012: The mechanism MUST include a means for providing the SRS
      with metadata describing CSs that are being recorded, including
      the media being used and the identifiers of parties involved.

   o  REQ-013: The mechanism MUST include a means for the SRS to be able
      to correlate RS media with CS participant media.

   o  REQ-014: Metadata format must be agnostic of the transport
      protocol.

   o  REQ-015: The mechanism MUST support a means to stop the recording.

   o  REQ-016: The mechanism MUST support a means for a recording-aware
      UA involved in a CS to request at session establishment time that
      the CS should be recorded or should not be recorded, the honoring
      of such a request being dependent on policy.

   o  REQ-017: The mechanism MUST support a means for a recording-aware
      UA involved in a CS to request during a session that the recording
      of the CS should be started, paused, resumed, or stopped, the
      honoring of such a request being dependent on policy.  Such
      recording-aware UAs MUST be notified about the outcome of such
      requests.

   o  REQ-018: The mechanism MUST NOT prevent the application of tones
      or announcements during recording or at the start of a CS to
      support notification to participants that the call is being
      recorded or may be recorded.

   o  REQ-019: The mechanism MUST provide a means of indicating to
      recording-aware UAs whether recording is taking place, for
      appropriate rendering at the user interface.

   o  REQ-020: The mechanism MUST provide a way for metadata to be
      conveyed to the SRS incrementally during the CS.

   o  REQ-021: The mechanism MUST NOT prevent high-availability
      deployments.

   o  REQ-022: The mechanism MUST provide means for facilitating
      synchronization of the recorded media streams and metadata.

   o  REQ-023: The mechanism MUST provide means for facilitating
      synchronization among the recorded media streams.

   o  REQ-024: The mechanism MUST provide means to relate recording and
      recording controls, such as start/stop/pause/resume, to the wall
      clock time.

   o  REQ-025: The mechanism MUST provide means for an SRS to
      authenticate the SRC on RS initiation.

   o  REQ-026: The mechanism MUST provide means for an SRC to
      authenticate the SRS on RS initiation.

   o  REQ-027: The mechanism MUST include a means for ensuring that the
      integrity of the metadata sent from the SRC to the SRS is an
      accurate representation of the original CS metadata.

   o  REQ-028: The mechanism MUST include a means for ensuring that the
      integrity of the media sent from the SRC to the SRS is an accurate
      representation of the original CS media.

   o  REQ-029: The mechanism MUST include a means for ensuring the
      confidentiality of the metadata sent from the SRC to the SRS.

   o  REQ-030: The mechanism MUST provide a means to support RS
      confidentiality.

   o  REQ-031: The mechanism MUST support the ability to deliver to the
      SRS multiple media streams of the same media type (e.g., audio,
      video).  One example is the case of delivering unmixed audio for
      each participant in the CS.

6.  Privacy Considerations

   Respecting the privacy rights and wishes of users engaged in a call
   is of paramount importance.  In many jurisdictions, participants have
   a right to know that the session is being recorded or might be
   recorded, and they have a right to opt out, either by terminating the
   call or by demanding that the call not be recorded.  Therefore, this
   document contains requirements for being able to notify users that a
   call is being recorded and for users to be able to request that a
   call not be recorded.  Use cases where users participating in a call
   are not informed that the call is or might be recorded are outside
   the scope of this document.  In particular, lawful intercept is
   outside the scope of this document.

   Requirements for participant notification of recording vary widely by
   jurisdiction.  In a given deployment, not all users will be
   authorized to stop the recording of a CS (although any user can
   terminate its participation in a CS).  Typically, users within the
   domain that is carrying out the recording will be subject to policies
   of that domain concerning whether CSs are recorded.  For example, in
   a call center, agents will be subject to policies of the call center
   and may or may not have the right to prevent the recording of a CS or
   part of a CS.  Users calling into the call center, on the other hand,
   will typically have to ask the agent not to record the CS.  If the
   agent is unable to prevent recording, or if the caller does not trust
   the agent, the only option generally is to terminate the CS.

   Privacy considerations also extend to what happens to a recording
   once it has been created.  Typical issues are who can access the
   recording (e.g., receive a copy of the recording, view the metadata,
   play back the media, etc.), for what purpose the recording can be
   used (e.g., for training purposes, for quality control purposes,
   etc.), and for how long the recording is to be retained before
   deletion.  These are typically policies of the domain that makes the
   recording, rather than policies of individual users involved in a
   recorded CS, whether those users be in the same domain or in a
   different domain.  Taking the call center example again, agents might
   be made aware of call center policy regarding retention and use of
   recordings as part of their employment contract, and callers from
   outside the call center might be given some information about policy
   when notified that a CS will be recorded (e.g., through an
   announcement that says that calls may be recorded for quality
   purposes).

   This document does not specify any requirements for a user engaged in
   a CS to be able to dictate policy for what happens to a recording, or
   for such information to be conveyed from an SRC to an SRS.  It is
   assumed that the SRS has access to policy applicable to its
   environment and can ensure that recordings are stored and used in
   accordance with that policy.

7.  Security Considerations

   Session recording has substantial security implications, for the SIP
   UAs being recorded, the SRC, and the SRS.

   For the SIP UAs involved in the Communication Session, the
   requirements in this document enable the UA to identify that a
   Communication Session is being recorded and to request that a given
   Communication Session not be subject to recording.

   Since humans don't typically look at or know about protocol signaling
   such as SIP, and indeed the SIP session might have originated through
   a Public Switched Telephone Network (PSTN) gateway without any
   ability to pass on in-signaling indications of recording, users can
   be notified of recording in the media itself through voice
   announcements, a visual indicator on the endpoint, or other means.

   With regard to security implications of the protocol(s), clearly
   there is a need for authentication, authorization, and eavesdropping
   protection for the solution.  The SRC needs to know the SRS it is
   communicating with is legitimate, and vice versa, even if they are in
   different domains.  Both the signaling and media for the Recording
   Session need the ability to be authenticated and protected from
   eavesdropping.  Requirements are detailed in Section 5.

   Communication Sessions and Recording Sessions can require different
   security levels both for signaling and media, depending on deployment
   configurations.  For some environments, e.g., the SRS and SRC will be
   collocated in a secure network region, and therefore the RS will not
   require the same protection level as a CS that extends over a public
   network, for example.  For other environments, the SRS can be located
   in a public cloud, for example, and the RS will require a higher
   protection level than the CS.  For these reasons, there is not a
   direct relationship between the security level of Communication
   Sessions and the security level of Recording Sessions.

   A malicious or corrupt SRC can tamper with media and metadata
   relating to a CS before sending the data to an SRS.  Also, CS media
   and signaling can be tampered with in the network prior to reaching
   an SRC, unless proper means are provided to ensure integrity
   protection during transmission on the CS.  Means for ensuring the
   correctness of media and metadata emitted by an SRC are outside the
   scope of this work.  Other organizational and technical controls will
   need to be used to prevent tampering.

8.  Acknowledgements

   Thanks to Dan Wing, Alan Johnson, Vijay Gurbani, Cullen Jennings,
   Hadriel Kaplan, Henry Lum, Dave Smith, Martin Palmer, Alissa Cooper,
   Deepanshu Gautam, Paul Kyzivat, Parthasarathi R, Ram Mohan R, and
   Charles Eckel for their significant contributions and assistance with
   this document and the SIPREC WG, and to all the members of the
   DISPATCH WG and SIPREC WG mailing lists for providing valuable input
   to this work.

9.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [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.

   [RFC4103]  Hellstrom, G. and P. Jones, "RTP Payload for Text
              Conversation", RFC 4103, June 2005.

   [RFC4733]  Schulzrinne, H. and T. Taylor, "RTP Payload for DTMF
              Digits, Telephony Tones, and Telephony Signals", RFC 4733,
              December 2006.

   [RFC4949]  Shirey, R., "Internet Security Glossary, Version 2",
              FYI 36, RFC 4949, August 2007.

Authors' Addresses

   Ken Rehor (editor)
   Cisco Systems
   170 West Tasman Dr.
   Mail Stop SJC30/2/
   San Jose, CA  95134
   USA

   EMail: krehor@cisco.com


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

   EMail: leon.portman@nice.com


   Andrew Hutton
   Siemens Enterprise Communications

   EMail: andrew.hutton@siemens-enterprise.com
   URI:   http://www.siemens-enterprise.com


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

   EMail: rajnish.jain@ipc.com