Content for TS 24.237 Word version: 17.2.0
1 Scope p. 16
IP Multimedia (IM) Core Network (CN) subsystem Service Continuity (SC) provides the capability of continuing ongoing communication sessions with multiple media across different access networks.
The present document provides the protocol details for enabling IMS SC based on the Session Initiation protocol (SIP) and the Session Description Protocol (SDP) and the protocols of the 3GPP Circuit-Switched (CS) domain (e.g. CAP, MAP, ISUP, BICC and the NAS call control protocol for the CS access).
The present document is applicable to User Equipment (UEs), Application Servers (AS), MSC Servers providing IMS Service Continuity capabilities, Emergency Access Transfer Function (EATF), Access Transfer Control Function (ATCF).
2 References p. 16
The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
- References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific.
- For a specific reference, subsequent revisions do not apply.
- For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.
[1]
TR 21.905: "Vocabulary for 3GPP Specifications".
[2]
TS 24.229: "IP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3".
[3]
TS 24.228: Release 5: "Signalling flows for the IP multimedia call control based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3".
[4]
TS 24.292: "IP Multimedia (IM) Core Network (CN) subsystem Centralized Services (ICS); Stage 3".
[5]
TS 24.216: "Communication continuity managed object".
[6]
TS 29.328: "IP Multimedia Subsystem (IMS) Sh interface; Signalling flows and message contents".
[7]
TS 29.329: "Sh interface based on the Diameter protocol; Protocol details".
[8]
TS 24.008: "Mobile radio interface layer 3 specification; Core Network protocols; Stage 3".
[9]
TS 23.237: "IP Multimedia subsystem (IMS) Service Continuity; Stage 2".
[10]
RFC 3891: "The Session Initiation Protocol (SIP) "Replaces" Header".
[11]
RFC 4538: "Request Authorization through Dialog Identification in the Session Initiation Protocol (SIP)".
[12]
TS 23.003: "Numbering, addressing and identification".
[13]
RFC 3515: "The Session Initiation Protocol (SIP) Refer Method".
[14] Void.
[15]
TS 23.228: "IP Multimedia Subsystem (IMS); Stage 2".
[16]
RFC 5012 (January 2008): "Requirements for Emergency Context Resolution with Internet Technologies".
[17]
RFC 5031 (January 2008): "A Uniform Resource Name (URN) for Services".
[18]
TS 29.292: "Interworking between the IP Multimedia (IM) Core Network (CN) subsystem and MSC Server for IMS Centralized Services (ICS)".
[19]
RFC 3261: "SIP: Session Initiation Protocol".
[20]
RFC 4488: "Suppression of Session Initiation Protocol (SIP) REFER Method Implicit Subscription".
[21]
RFC 3023: "XML Media Types".
[22]
RFC 5626: "Managing Client Initiated Connections in the Session Initiation Protocol (SIP)".
[23]
TS 24.286: "IP Multimedia (IM) Core Network (CN) subsystem Centralised Services (ICS); Management Object (MO)".
[24]
TS 22.173: "IP Multimedia Core Network Subsystem (IMS) Multimedia Telephony Service and supplementary services; Stage 1".
[25]
TS 24.607: "Originating Identification Presentation (OIP) and Originating Identification Restriction (OIR) using IP Multimedia (IM) Core Network (CN) subsystem; Protocol Specification".
[26]
TS 24.608: "Terminating Identification Presentation (TIP) and Terminating Identification Restriction (TIR) using IP Multimedia (IM)Core Network (CN) subsystem; Protocol Specification".
[27]
TS 24.604: "Communication Diversion (CDIV) using IP Multimedia (IM)Core Network (CN) subsystem; Protocol specification".
[28]
TS 24.610: "Communication HOLD (HOLD) using IP Multimedia (IM) Core Network (CN) subsystem; Protocol specification".
[29]
TS 24.611: "Anonymous Communication Rejection (ACR) and Communication Barring (CB); using IP Multimedia (IM) Core Network (CN) subsystem; Protocol specification".
[30]
TS 24.606: "Message Waiting Indication (MWI) using IP Multimedia (IM) Core Network (CN) subsystem; Protocol specification".
[31]
TS 24.605: "Conference (CONF) using IP Multimedia (IM) Core Network (CN) subsystem; Protocol specification".
[32]
TS 24.629: "Explicit Communication Transfer (ECT) using IP Multimedia (IM) Core Network (CN) subsystem; Protocol specification".
[33]
TS 24.647: "Advice Of Charge (AOC) using IP Multimedia (IM)Core Network (CN) subsystem; Protocol Specification".
[34]
TS 24.654: "Closed User Group (CUG) using IP Multimedia (IM) Core Network (CN) subsystem, Protocol Specification".
[35]
TS 24.239: "Flexible Alerting (FA) using IP Multimedia (IM) Core Network (CN) subsystem; Protocol specification".
[36]
TS 24.615: "Communication Waiting (CW) using IP Multimedia (IM) Core Network (CN) subsystem; Protocol Specification".
[37]
TS 24.642: "Completion of Communications to Busy Subscriber (CCBS) and Completion of Communications by No Reply (CCNR) using IP Multimedia (IM)Core Network (CN) subsystem; Protocol Specification".
[38]
TS 24.182: "IP Multimedia Subsystem (IMS) Customized Alerting Tones (CAT); Protocol specification".
[39]
TS 24.616: "Malicious Communication Identification (MCID) using IP Multimedia (IM) Core Network (CN) subsystem; Protocol Specification".
[40]
TS 24.259: "Personal Network Management (PNM); Stage 3".
[41]
TS 24.183: "IP Multimedia Subsystem (IMS) Customized Ringing Signal (CRS) service; Stage 3".
[42]
TS 24.072: "Call Deflection (CD) Supplementary Service; Stage 3".
[43]
TS 24.083: "Call Waiting (CS) and Call Hold (HOLD) supplementary services; Stage 3".
[44]
TS 24.294: "IP Multimedia Subsystem (IMS) Centralized Services (ICS) protocol via I1 interface".
[45] Void.
[46]
TS 24.091: "Explicit Call Transfer (ECT) supplementary service; Stage 3".
[47]
TS 24.084: "Multi Party (MPTY) supplementary service;Stage 3".
[48]
RFC 4235 (November 2005): "An INVITE-Initiated Dialog Event Package for the Session Initiated Protocol (SIP)"..
[49]
TS 23.216: "Single Radio Voice Call Continuity (SRVCC); Stage 2".
[50] Void.
[51] Void.
[52]
TS 24.301: "Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3".
[53]
RFC 3840 (August 2004): "Indicating User Agent Capabilities in the Session Initiation Protocol (SIP)".
[54]
RFC 6086 (January 2011): "Session Initiation Protocol (SIP) INFO Method and Package Framework".
[55]
RFC 4353 (February 2006): "A Framework for Conferencing with the Session Initiation Protocol (SIP)".
[56] Void.
[57]
RFC 3326 (December 2002): "The Reason Header Field for the Session Initiation Protocol (SIP)".
[58]
RFC 3264 (June 2002) "An Offer/Answer Model with the Session Description Protocol (SDP)".
[59] Void.
[60]
RFC 6809 (November 2012): "Mechanism to Indicate Support of Features and Capabilities in the Session Initiation Protocol (SIP)".
[61]
TS 25.331: "Radio Resource Control (RRC); protocol specification".
[62]
TS 36.331: "Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification".
[63]
TS 23.292: "IP Multimedia Subsystem (IMS) Centralized Services; Stage 2".
[64]
TS 24.337: "IP Multimedia (IM) Core Network (CN) subsystem; inter-UE transfer; Stage 3".
[65]
TS 23.203: "Policy and charging control architecture".
[66]
TS 23.107: "Quality of Service (QoS) concept and architecture".
[67]
TS 23.218: "IP Multimedia (IM) Session Handling; IM call model".
[68]
TS 26.114: "IP Multimedia Subsystem (IMS); Multimedia Telephony; Media handling and interaction".
[69]
TS 26.111: "Codec for circuit switched multimedia telephony service; Modifications to H.324".
[70]
TS 29.274: "Tunnelling Protocol for Control plane (GTPv2-C); Stage 3".
[71]
TS 29.280: "3GPP Sv interface (MME to MSC, and SGSN to MSC) for SRVCC".
[72]
RFC 3263 (June 2002): "Session Initiation Protocol (SIP): Locating SIP Servers".
[73]
RFC 7195 (May 2014): "Session Description Protocol (SDP) Extension for Setting Audio and Video Media Streams over Circuit-Switched Bearers in the Public Switched Telephone Network (PSTN)".
[74]
RFC 6157 (April 2011): "IPv6 Transition in the Session Initiation Protocol (SIP)".
[75]
TS 24.007: "Mobile radio interface signalling layer 3; General aspects".
[76]
ETSI TS 182 024: "Hosted Enterprise Services; Architecture, functional description and signalling".
[77]
TS 29.079: "Optimal media routeing within the IP Multimedia Subsystem (IMS)".
[78]
RFC 3841 (August 2004): "Caller Preferences for the Session Initiation Protocol (SIP)".
[79]
RFC 3966 (December 2004): "The tel URI for Telephone Numbers".
[80]
RFC 6228 (May 2011): "Session Initiation Protocol (SIP) Response Code for Indication of Terminated Dialog".
[81]
RFC 6665 (July 2012): "SIP-Specific Event Notification".
[82]
RFC 7254 (May 2014): "A Uniform Resource Name Namespace for the Global System for Mobile Communications Association (GSMA) and the International Mobile station Equipment Identity (IMEI)".
[83]
RFC 7549 (May 2015): "3GPP SIP URI Inter-Operator Traffic Leg Parameter".
[84]
TS 24.302: "Access to the 3GPP Evolved Packet Core (EPC) via non-3GPP access networks".
[85]
TS 32.260: "Telecommunication management; Charging management".
[86]
RFC 3262 (June 2002 ): "Reliability of Provisional Responses in the Session Initiation Protocol (SIP)".
[87]
RFC 3311 (September 2002): "The Session Initiation Protocol (SIP) UPDATE Method".
[88]
RFC 3312 (October 2002): "Integration of Resource Management and Session Initiation Protocol (SIP)".
[89]
RFC 4032 (March 2005): "Update to the Session Initiation Protocol (SIP) Preconditions Framework".
[90]
RFC 7647 (September 2015): "Clarifications for the Use of REFER with RFC6665".
[91]
RFC 3551 (July 2003): "RTP Profile for Audio and Video Conferences with Minimal Control".
[92]
RFC 3550 (July 2003): "RTP: A Transport Protocol for Real-Time Applications".
[93]
RFC 4566 (July 2006): "SDP: Session Description Protocol".
[94]
RFC 8497 (November 2018): "Marking SIP Messages to Be Logged".
[95]
TS 24.147: "Conferencing using the IP Multimedia (IM) Core Network (CN) subsystem; Stage 3".
[96]
TS 23.501: "System Architecture for the 5G System; Stage 2".
[97]
TS 23.502: "Procedures for the 5G System".
[98]
TS 24.501: "Non-Access-Stratum (NAS) protocol for 5G System (5GS); Stage 3".
[99]
TS 29.562: "Home Subscriber Server (HSS) Services for interworking with the IP Multimedia Subsystem (IMS); Stage 3".
3 Definitions and abbreviations |R15| p. 20
3.1 Definitions p. 20
For the purposes of the present document, the terms and definitions given in TR 21.905 and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905.
Alerting phase:
Refers to a SIP session for which all possibly existing dialogs created by the SIP INVITE request initiating the session are early dialogs, for which no final SIP response has been received yet and for which SIP 180 (Ringing) response has already been received in an existing early dialogs.
Pre-alerting phase:
Refers to a SIP session for which all possibly existing dialogs created by the SIP INVITE request initiating the session are early dialogs, for which no final SIP response has been received yet and for which SIP 180 (Ringing) response has not been received or sent yet in any existing early dialogs.
Dual radio access transfer for calls in alerting phase:
feature enabling dual radio access transfer of a session with speech media component where the session is in an alerting phase.
Dual radio access transfer for originating calls in pre-alerting phase:
feature enabling dual radio access transfer of a session with speech media component where the session was originated by the SC UE and the session is in a pre-alerting phase.
Dynamic STI:
An STI dynamically assigned by the SCC AS, representing the SIP dialog identifier (Call-ID header field and the values of tags in To and From header fields) and used for session transfer request when Gm service control is available.
Dynamic STN:
An STN encoded as an E.164 number in tel URI format dynamically assigned by the SCC AS replacing the static STN during PS to CS dual radio access transfer.
Static STN:
An STN configured in the SC UE as an E.164 number. The static STN is used for PS to CS transfer when dynamic STN cannot be used.
Additional transferred session SCC AS URI:
A SIP URI which is a public service identity hosted by SCC AS and which is used during PS-CS access transfer with the MSC Server assisted mid-call feature.
Static STI:
An STI configured in the SC UE either as a SIP URI or as an E.164 number in tel URI format or SIP URI representation of tel URI. The static STI is used for CS-PS transfer when dynamic STI is unavailable.
PS to PS STI:
An STI configured in SC UE either as a SIP URI or as an E.164 number in tel URI format or SIP URI representation of tel URI. The PS to PS STI is used for PS to PS access transfer.
PS to CS STN:
An STN that is encoded as an E.164 number. The PS to CS STN is used for PS to CS access transfer.
Speech media component:
SDP media component of audio media type with codec suitable for conversational speech. Connection (c=) and attribute (a=) informations at the SDP session level not overridden by information at the SDP media level in the speech media component are considered to be part of the speech media component.
Active speech media component:
speech media component which has "recvonly" or "sendrecv" directionality at the SC UE or at the MSC server serving the SC UE.
Inactive speech media component:
speech media component which has "sendonly" or "inactive" directionality at the SC UE or at the MSC server serving the SC UE.
Active video media component:
video media component which has "recvonly" or "sendrecv" directionality at the SC UE or at the MSC server serving the SC UE.
Inactive video media component:
video media component which has "sendonly" or "inactive" directionality at the SC UE or at the MSC server serving the SC UE.
ATCF URI for originating requests:
A URI of the ATCF where the ATCF receives requests sent by the served UEs.
ATCF URI for terminating requests:
A URI of the ATCF where the ATCF receives requests targeted to the served UEs.
ATCF management URI:
A URI hosted by the ATCF where the ATCF performing the role of a UAS receives SIP requests for ATCF management (e.g. SIP MESSAGE requests containing the PS to CS SRVCC related information). The ATCF management URI is routable via the I-CSCF in the network where the ATCF is located using the same routing mechanism as used for Public Service Identities hosted by an AS.
Registration Path:
The set of Path header field values and the set of Service-Route header field values created by successful completion of the SIP REGISTER transaction.
SRVCC-related information:
Information required by the ATCF to perform PS to CS SRVCC transfer or CS to PS SRVCC transfer or both. It is provided in the MIME body as defined in clause D.3.
UE information for CS to PS SRVCC:
Session description containing speech media component that will be used by the ATGW to send media to the SC UE during the CS to PS SRVCC access transfer.
ATGW information for CS to PS SRVCC:
Session description containing speech media component that will be used by the SC UE to send media to the ATGW during the CS to PS SRVCC access transfer.
PS to CS SRVCC for calls in alerting phase:
feature enabling PS to CS SRVCC of a session with speech media component where the session is in alerting phase.
CS to PS SRVCC for calls in alerting phase:
feature enabling CS to PS SRVCC of a session with speech media component where the session is in alerting phase.
PS to CS SRVCC for originating calls in pre-alerting phase:
feature enabling PS to CS SRVCC of a session with speech media component where the session was originated by the SC UE and the session is in pre-alerting phase.
PS to CS SRVCC for terminating calls in pre-alerting phase:
feature enabling PS to CS SRVCC of a session with speech media component where the session was terminated by the SC UE and the session is in pre-alerting phase.
CS session in an early phase:
A CS call for which the CS call setup procedure is not complete, i.e. the CC CONNECT message is not sent or received as described in TS 24.008 yet but where either a CC CALL PROCEEDING message as described in TS 24.008 has been received or a CC ALERTING message as described in TS 24.008 has been sent or received.
Precondition enabled dialog:
a dialog (either a confirmed dialog or an early dialog) created by a SIP response containing a Require header field with the precondition option tag.
Precondition enabled initial INVITE request:
an initial INVITE request containing a Require header field with the precondition option tag or a Supported header field with the precondition option tag.
RTP payload format:
the <encoding name> portion of an "a=rtpmap" attribute according to IETF RFC 4566 [93] for the dynamically assigned RTP payload type numbers or the name of encoding reserved in IETF RFC 3551 [91] table 1 for statically assigned RTP payload type numbers.
RTP payload type number:
a number identifying an RTP payload type of a media stream using the RTP based transport protocol. In SDP, the RTP payload type number can be found in a sub-field of an <fmt> portion of an "m=" line, in a <payload type> portion of the "a=rtpmap" attribute and in a <format> portion of an "a=fmtp" attribute, according to IETF RFC 4566 [93]. In RTP, the RTP payload type number is found in the PT field of the RTP header according to IETF RFC 3550 [92].
RTP payload type:
an RTP payload type number indicated in a sub-field of an <fmt> portion of an "m=" line and, if included, an "a=rtpmap" attribute and an "a=fmtp" attribute for the RTP payload type number, included in an SDP body, according to IETF RFC 4566 [93].
For the purposes of the present document, the following terms and definitions given in TS 23.237 apply:
Access Leg
Access Transfer Control Function (ATCF)
Access Transfer Gateway (ATGW)
Access Transfer Update - Session Transfer Identifier (ATU-STI)
Dual radio
Emergency Session Transfer Number for SR VCC (E-STN-SR)
Home Leg
Local Operating Environment
Remote Leg
Serving Leg Session Transfer Identifier for reverse SRVCC (STI-rSR)
Source Access Leg
Target Access Leg
Emergency Session Transfer Number for DRVCC (E-STN-DRVCC)
For the purposes of the present document, the following terms and definitions given in TS 24.292 apply:
CS call
CS media
For the purposes of the present document, the following terms and definitions given in TS 23.218 apply:
Initial filter criteria
For the purposes of the present document, the following terms and definitions given in TS 23.228 apply:
Policy and Charging Rule Function (PCRF)
For the purposes of the present document, the following terms and definitions given in TS 23.003 apply:
Correlation MSISDN
IP Multimedia Routeing Number (IMRN)
Session Transfer Identifier (STI)
Session Transfer Number (STN)
Session Transfer Number for SR-VCC (STN-SR)
For the purposes of the present document, the following terms and definitions given in IETF RFC 5012 [16] apply:
Emergency service URN
For the purposes of the present document, the following terms and definitions given in IETF RFC 4353 [55] apply:
Conference
Conference URI
Focus
Participant
For the purposes of the present document, the following terms and definitions given in IETF RFC 3264 [58] apply:
Directionality
For the purposes of the present document, the following terms and definitions given in TS 23.292 apply:
ICS user
For the purposes of the present document, the following terms and definitions given TS 24.229 apply:
Authorised Resource-Priority header field
Temporarily Authorised Resource-Priority header field
For the purposes of the present document, the following terms and definitions given in TS 24.301 apply:
Evolved Packet System (EPS)
Persistent EPS bearer context
For the purposes of the present document, the following terms and definitions given in TS 23.501 apply:
5G System (5GS)
NG-RAN
Non-3GPP InterWorking Function (N3IWF)
Protocol Data Unit (PDU) session
For the purposes of the present document, the following terms and definitions given in TS 24.501 apply:
Persistent PDU session context
For the purposes of the present document, the following terms and definitions given TS 29.274 apply:
Allocation/Retention Priority (ARP)
For the purposes of the present document, the following terms and definitions given TS 23.216 apply:
5G SRVCC
3.2 Abbreviations p. 23
For the purposes of the present document, the abbreviations given in TR 21.905 and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in TR 21.905.
1xx
A SIP status-code in the range 101 through 199
18x
A SIP status-code in the range 180 through 189
2xx
A SIP status-code in the range 200 through 299
EATF
Emergency Access Transfer Function
E-STN-SR
Emergency Call Session Transfer Number - Single Radio
E-SR-VCC
Emergency Single Radio Voice Call Continuity
C-MSISDN
Correlation MSISDN
IMRN
IP Multimedia Routing Number
SC
Service Continuity
SCC
Service Centralization and Continuity
SM
Session Management
SRVCC
Single Radio Voice Call Continuity
STI
Session Transfer Identifier
STI-rSR
Session Transfer Identifier for reverse SRVCC
STN
Session Transfer Number
STN-SR
Session Transfer Number - Single Radio
vSRVCC
Single Radio Video Call Continuity
