3GPP TS 29.280: Evolved Packet System (EPS); 3GPP Sv interface (MME to MSC, and SGSN to MSC) for SRVCC

3GPP TS 29.280 V9.9.0 (2014-06)
Technical Specification
3rd Generation Partnership Project;
Technical Specification Group Core Network and Terminals;
Evolved Packet System (EPS);
3GPP Sv interface (MME to MSC, and SGSN to MSC) for SRVCC 
 (Release 9)
	 EMBED Word.Picture.8  
The present document has been developed within the 3rd Generation Partnership Project (3GPP TM) and may be further elaborated for the purposes of 3GPP.	
The present document has not been subject to any approval process by the 3GPP Organizational Partners and shall not be implemented.	
This Specification is provided for future development work within 3GPP only. The Organizational Partners accept no liability for any use of this Specification.
Specifications and reports for implementation of the 3GPP TM system should be obtained via the 3GPP Organizational Partners' Publications Offices.


Keywords
LTE, UMTS, packet mode, network

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Contents
 TOC \o "1-9" Foreword	 PAGEREF _Toc390767360 \h 4
1	Scope	 PAGEREF _Toc390767361 \h 5
2	References	 PAGEREF _Toc390767362 \h 5
3	Definitions, symbols and abbreviations	 PAGEREF _Toc390767363 \h 5
3.1	Definitions	 PAGEREF _Toc390767364 \h 5
3.2	Symbols	 PAGEREF _Toc390767365 \h 6
3.3	Abbreviations	 PAGEREF _Toc390767366 \h 6
4	General Description	 PAGEREF _Toc390767367 \h 6
5	Sv Messages and Information Elements	 PAGEREF _Toc390767368 \h 6
5.1	Introduction	 PAGEREF _Toc390767369 \h 6
5.2	Sv Messages	 PAGEREF _Toc390767370 \h 6
5.2.1	General	 PAGEREF _Toc390767371 \h 6
5.2.2	SRVCC PS to CS Request	 PAGEREF _Toc390767372 \h 7
5.2.3	SRVCC PS to CS Response	 PAGEREF _Toc390767373 \h 9
5.2.4	SRVCC PS to CS Complete Notification	 PAGEREF _Toc390767374 \h 9
5.2.5	SRVCC PS to CS Complete Acknowledge	 PAGEREF _Toc390767375 \h 10
5.2.6	SRVCC PS to CS Cancel Notification	 PAGEREF _Toc390767376 \h 10
5.2.7	SRVCC PS to CS Cancel Acknowledge	 PAGEREF _Toc390767377 \h 10
5.3	Path Management Messages	 PAGEREF _Toc390767378 \h 11
5.3.1	Introduction	 PAGEREF _Toc390767379 \h 11
5.3.2	Echo Request message	 PAGEREF _Toc390767380 \h 11
5.3.3	Echo Response message	 PAGEREF _Toc390767381 \h 11
5.3.4	Version Not Supported message	 PAGEREF _Toc390767382 \h 11
5.4	Reliable Delivery of Signalling Messages	 PAGEREF _Toc390767383 \h 11
5.5	Error Handling	 PAGEREF _Toc390767384 \h 11
5.6	Restoration and Recovery	 PAGEREF _Toc390767385 \h 11
6	Sv Information Elements	 PAGEREF _Toc390767386 \h 11
6.1	General	 PAGEREF _Toc390767387 \h 11
6.2	STN-SR	 PAGEREF _Toc390767388 \h 12
6.3	Source to Target Transparent Container	 PAGEREF _Toc390767389 \h 12
6.4	Target to Source Transparent Container	 PAGEREF _Toc390767390 \h 13
6.5	MM Context for E-UTRAN SRVCC	 PAGEREF _Toc390767391 \h 13
6.6	MM Context for UTRAN SRVCC	 PAGEREF _Toc390767392 \h 14
6.7	SRVCC Cause	 PAGEREF _Toc390767393 \h 15
6.8	Target RNC ID	 PAGEREF _Toc390767394 \h 15
6.9	Target Global Cell ID	 PAGEREF _Toc390767395 \h 15
6.10	Tunnel Endpoint Identifier for Control Plane (TEID-C)	 PAGEREF _Toc390767396 \h 15
6.11	Sv Flags	 PAGEREF _Toc390767397 \h 16
6.12	Service Area Identifier	 PAGEREF _Toc390767398 \h 16
Annex A (informative):	Change history	 PAGEREF _Toc390767399 \h 17

Foreword
This Technical Specification has been produced by the 3rd Generation Partnership Project (3GPP).
The contents of the present document are subject to continuing work within the TSG and may change following formal TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an identifying change of release date and an increase in version number as follows:
Version x.y.z
where:
x	the first digit:
1	presented to TSG for information;
2	presented to TSG for approval;
3	or greater indicates TSG approved document under change control.
y	the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections, updates, etc.
z	the third digit is incremented when editorial only changes have been incorporated in the document.
1	Scope
The present document describes the Sv interface between the Mobility Management Entity (MME) or Serving GPRS Support Node (SGSN) and 3GPP MSC server enhanced for SRVCC. Sv interface is used to support Inter-RAT handover from VoIP/IMS over EPS to CS domain over 3GPP UTRAN/GERAN access or from UTRAN (HSPA) to 3GPP UTRAN/GERAN access.
If there is no specific indication, the term "MSC server" denotes 3GPP MSC server enhanced for SRVCC as defined in 3GPP TS 23.216 [2].
2	References
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]	3GPP TR 21.905: "Vocabulary for 3GPP Specifications".
[2]	3GPP TR 23.216: "Single Radio Voice Call Continuity (SRVCC)".
[3]	3GPP TS 29.274: "Evolved GPRS Tunnelling Protocol for Control Plane (GTPv2-C)".
[4]	3GPP TS 23.003: "Numbering, addressing and identification".
[5]	3GPP TS 23.007: "Restoration Procedures".
[6]	3GPP TS 33.401: "3GPP System Architecture Evolution (SAE): Security architecture".
[7]	3GPP TS 24.008: "Mobile radio interface Layer 3 specification; Core network protocols; Stage 3".
[8]	3GPP TS 48.008: "Mobile Switching Centre – Base Station System (MSC - BSS) interface; Layer 3 specification".
[9]	3GPP TS 25.413: "UTRAN Iu interface Radio Access Network Application Part (RANAP) signalling".
[10]	3GPP TS 33.102: "3G Security; Security architecture".
[11]	3GPP TS 29.002: "Mobile Application Part (MAP) specification; Stage 3".
[12]	3GPP TS 24.301: "Non-Access-Stratum (NAS) protocol for Evolved Packet".
3	Definitions, symbols and abbreviations
3.1	Definitions
For the purposes of the present document, the terms and definitions given in 3GPP TR 21.905 [1] and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in 3GPP TR 21.905 [1].
3.2	Symbols
For the purposes of the present document, the following symbols apply:
3.3	Abbreviations
For the purposes of the present document, the abbreviations given in 3GPP TR 21.905 [1] and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in 3GPP TR 21.905 [1].
STN-SR	Session Transfer Number for SRVCC: see 3GPP TS 23.003 [4].
MME/SGSN	MME or SGSN.
C-MSISDN	Correlation MSISDN.
4	General Description
This document describes the Sv interface related procedures, message parameters and protocol specifications. The Sv messages are based on GTP. The message format, IE coding, and protocol error handling for Sv is per GTP as specified in 3GPP TS 29.274 [3]. 
The general rules for IP address and UDP port number handling for the GTP messages on the Sv interface is per 3GPP TS 29.274 [3].
5	Sv Messages and Information Elements
5.1	Introduction
The Sv application defines a set of messages between the MME/SGSN and MSC Server to provide SRVCC as defined in 3GPP TS 23.216 [2]. The Sv message header is defined in 3GPP TS 29.274 [3]. The messages to be used and the information elements are described in the following sections.
5.2	Sv Messages
5.2.1	General
Sv Message Type value is defined in 3GPP TS 29.274 [3]. The message format is coded as per GTP in 3GPP TS 29.274 [3].
Table 5.2.1: Message types for Sv interface
Message Type value (Decimal)
Message
Reference
0
Reserved
3GPP TS 29.274 [3]
1
Echo Request
3GPP TS 29.274 [3]
2
Echo Response
3GPP TS 29.274 [3]
3
Version Not Supported Indication
3GPP TS 29.274 [3]
4-24
Reserved for S101 interface
3GPP TS 29.274 [3]
25
SRVCC PS to CS Request
5.2.2
26
SRVCC PS to CS Response
5.2.3
27
SRVCC PS to CS Complete Notification
5.2.4
28
SRVCC PS to CS Complete Acknowledge
5.2.5
29
SRVCC PS to CS Cancel Notification
5.2.6
30
SRVCC PS to CS Cancel Acknowledge
5.2.7
31
For future Sv interface use
-
32-255
Reserved for GTPv2 
3GPP TS 29.274 [3]

The GTPv2-C messages shall be sent per UE on the Sv interface.
There shall be one pair of TEID-C per UE on the Sv interface. The same tunnel shall be shared for the control messages related to the same UE operation.
The TEID field in the SRVCC PS to CS Request message header shall be set to "0" because this is the first message the the MME/SGSN sends to the MSC server to establish the tunnel for a UE. 
The TEID field in the SRVCC PS to CS Cancel Notification message header shall be set to "0" if the message is sent before reception of the acceptance response to the SRVCC PS to CS Request. If the MME/SGSN sends the SRVCC PS to CS Cancel Notification message after the acceptance response to the SRVCC PS to CS Request, the TEID field of the SRVCC PS to CS Cancel Notification message may be set to the MSC Server’s TEID value received in the SRVCC PS to CS Response message. Therefore the MSC Server shall be able to accept the SRVCC PS to CS Cancel Notification messages with "0" or non-zero TEID in the message header.
5.2.2	SRVCC PS to CS Request
A SRVCC PS to CS Request message shall be sent across Sv interface from the MME/SGSN to the target MSC server as part of the MME/SGSN SRVCC procedure in 3GPP TS 23.216 [2].
Table 5.2.2 specifies the presence requirements and conditions of the IEs in the message.
Table 5.2.2: Information Elements in a SRVCC PS to CS Request 
Information elements
P
Condition / Comment
IE Type
Ins.
IMSI
C
This IE shall be included in the message except for the cases:
The UE is emergency attached and it is UICCless
The UE is emergency attached and the IMSI is not authenticated
IMSI
0
ME Identity (MEI)
C
This IE shall be included in the message for the following cases: 
The UE is emergency attached and it is UICCless
The UE is emergency attached and the IMSI is not authenticated
MEI
0
CO
This IE shall be included for all SRVCC calls if available in the MME or SGSN (NOTE 2).
Sv Flags
C
The following flags are applicable:
EmInd: this flag shall be sent if this session is for an emergency call.
ICS: this flag shall be sent to request IMS Centralized Service support.
Sv Flags
0
MME/SGSN Sv Address for Control Plane
M
This IE specifies the address for control plane message which is chosen by the source MME/SGSN
IP-Address
0
MME/SGSN Sv TEID for Control Plane
M
This IE specifies the tunnel for control plane message which is chosen by the source MME/SGSN. The target MM shall include this TEID in the GTP header of all related control plane messages which are related to the requested bearer.
TEID-C
0
C-MSISDN
C
The MME/SGSN shall include C-MSISDN IE in the message except for the cases:
The UE is emergency attached and it is UICCless
The UE is emergency attached and the IMSI is not authenticated
The C-MSISDN is defined in 3GPP TS 23.003 [4].
MSISDN
0
STN-SR
C
The MME/SGSN shall include STN-SR IE if this session is not for an emergency call.
STN-SR
0
MM Context for E-UTRAN SRVCC
C
The MME shall include mobile station classmarks, supported codecs, and CS Security key in MM Context for SRVCC for E-UTRAN SRVCC. 
The derivation of the CS security keys shall follow the procedures defined 3GPP TS 33.401[7].
MM Context for E-UTRAN SRVCC
0
MM Context for UTRAN SRVCC
C
The SGSN shall include mobile station classmarks, supported codecs, and CS Security key in MM Context for SRVCC for UTRAN (HSPA) SRVCC. 
The derivation of the CS security keys shall follow the procedures defined 3GPP TS 33.102[10].
MM Context for UTRAN SRVCC
0
Source to Target Transparent Container
M
 The MME or SGSN shall include Source to Target Transparent Container IE
Source to Target Transparant Container IE
0
Target RNC ID 
C
This IE shall be used to identify the target access for SRVCC handover to UTRAN (NOTE 1).
Target RNC ID 
0
Target Cell ID
C
This IE shall be used to identify the target access for SRVCC handover to GERAN (NOTE 1).
Target Global Cell 
ID
0
Source SAI
CO
The SGSN shall include this IE during a SRVCC Handover from UTRAN to GERAN and shall set it as per the SAI of the Source ID IE received from the source RNC (see 3GPP TS 25.413 [9]). See NOTE 3.
Service Area Identifier
0
Private Extension
O
None
Private Extension
VS
NOTE 1:	Based upon the SRVCC Handover procedure, either Target RNC ID or Target Cell ID shall be present in this message
NOTE 2:	An MME or SGSN supporting the Sv interface should attempt to get the ME Identity for all SRVCC calls for interception, charging or Automatic Device Detection in the MSC. 
NOTE 3: 	The Source SAI is sent in BSSMAP Handover Request during a SRVCC Handover from UTRAN to GERAN. A default SAI configured in the MSC Server enhanced for SRVCC is sent in BSSMAP Handover Request during a SRVCC Handover from E-UTRAN to GERAN. The default SAI for E-UTRAN should be different from the SAIs used in UTRAN.
	
5.2.3	SRVCC PS to CS Response
A SRVCC PS to CS Response message shall be sent across Sv interface as a response to SRVCC PS to CS Request by the MSC server during SRVCC procedure in 3GPP TS 23.216 [2].
Table 5.2.3 specifies the presence requirements and conditions of the IEs in the message.
Cause IE indicates if the SRVCC PS to CS request has been accepted, or not. The request has not been accepted by the target MSC server if the Cause IE value differs from "Request accepted". 
Table 5.2.3: Information Elements in a SRVCC PS to CS Response 
Information elements
P
Condition / Comment
IE Type
Ins.
Cause
M

Cause
0
SRVCC rejected Cause
O
This IE may be sent if Cause value is differs from "Request accepted".  
MSC Server may include additional information to indicate the reason for rejecting SRVCC PS to CS request 
SRVCC Cause
0
MSC Server Sv Address for Control Plane
O
If the Cause IE contains the value" Request accepted", the target MSC server may include MSC server Sv Address for Control Plane IE in SRVCC PS to CS Response message if target MSC Server decides to use different IP address for the subsequent communication. The source MME/SGSN shall store this MSC server address and use it when sending subsequent control plane messages to this GTP-C tunnel.
IP Address
0
MSC Server Sv TEID for Control Plane
C
The target MSC server shall include MSC server Sv Tunnel Endpoint Identifier for Control Plane IE in SRVCC PS to CS Response message if the Cause IE contains the value "Request accepted". The source MME/SGSN shall include this TEID-C in the GTP-C header of all subsequent uplink control plane messages from the source MME/SGSN to the target MSC servers.
TEID-C
0
Target to Source Transparent Container
C
If the Cause IE contains the value "Request accepted ", this IE shall be included and shall carry the Target to Source Transparent Container to be sent within the Handover command or the Relocation Command towards the source access network.
Target to Source Transparant Container IE
0
Private Extension
O
None
Private Extension
VS

5.2.4	SRVCC PS to CS Complete Notification
A SRVCC PS to CS Complete Notification message shall be sent across Sv interface to the source MME/SGSN to indicate the SRVCC handover with CS Domain has been successfully finished during SRVCC procedure in 3GPP TS 23.216 [2].
Table 5.2.4 specifies the presence requirements and conditions of the IEs in the message.
Table 5.2.4: Information Elements in a SRVCC PS to CS Complete Notification
Information elements
P
Condition / Comment
IE Type
Ins.
IMSI
C
This IE shall be included in the message except for the cases:
The UE is emergency attached and it is UICCless
The UE is emergency attached and the IMSI is not authenticated
IMSI
0
Private Extension
O
None
Private Extension
VS

5.2.5	SRVCC PS to CS Complete Acknowledge
A SRVCC PS to CS Complete Acknowledge message shall be sent across Sv interface as a response to SRVCC PS to CS Complete Notification during SRVCC handover with CS Domain in 3GPP TS 23.216 [2].
Table 5.2.5 specifies the presence requirements and conditions of the IEs in the message.
Table 5.2.5: Information Elements in a SRVCC PS to CS Complete Acknowledge
Information elements
P
Condition / Comment
IE Type
Ins.
Cause
M
None
Cause
0
Private Extension
O
None
Private Extension
VS

5.2.6	SRVCC PS to CS Cancel Notification
A SRVCC PS to CS Cancel Notification message shall be sent across Sv interface from the MME/SGSN to the target MSC server to request the cancellation of an ongoing SRVCC handover.
Table 5.2.6 specifies the presence requirements and conditions of the IEs in the message.
Table 5.2.6: Information Elements in a SRVCC PS to CS Cancel Notification 
Information elements
P
Condition / Comment
IE Type
Ins.
IMSI
C
 This IE shall be included in the message except for the cases:
The UE is emergency attached and it is UICCless
The UE is emergency attached and the IMSI is not authenticated
IMSI
0
Cancel Cause
M
MME/SGSN  indicates  the reason for Handover cancellation
SRVCC Cause
0
ME Identity (MEI)
C
This IE shall be included in the message for the following cases:
The UE is emergency attached and it is UICCless
The UE is emergency attached and the IMSI is not authenticated
MEI
0
Private Extension
O
None
Private Extension
VS

5.2.7	SRVCC PS to CS Cancel Acknowledge
A SRVCC PS to CS Cancel Acknowledge message shall be sent across Sv interface as a response to SRVCC PS to CS Cancel Notification.
Table 5.2.7 specifies the presence requirements and conditions of the IEs in the message.
Table 5.2.7: Information Elements in a SRVCC PS to CS Cancel Acknowledge
Information elements
P
Condition / Comment
IE Type
Ins.
Cause
M
None
Cause
0
Sv Flags
C
The following flags are applicable:
STI: this flag shall be sent if the MSC Server has started the IMS session transfer procedure.
Sv Flags
0
Private Extension
O
None
Private Extension
VS

5.3	Path Management Messages
5.3.1	Introduction
The following GTP-C v2 messages support path management for the Sv interface:
Echo Request
Echo Response
Version Not Supported
These messages are defined for GTP-Cv2 and the handling and definition shall also be as defined in GTP-Cv2, see 3GPP TS 29.274 [3].
5.3.2	Echo Request message
3GPP TS 29.274 [6] specifies the information elements included in the Echo Request message.
5.3.3	Echo Response message
3GPP TS 29.274 [3] specifies the information elements included in the Echo Response message.
5.3.4	Version Not Supported message
3GPP TS 29.274 [3] specifies the detailed handling and information elements included in the Version Not Supported message.
5.4	Reliable Delivery of Signalling Messages
This is performed as according to GTPv2 in 3GPP TS 29.274 [3].
5.5	Error Handling 
This is performed as according to GTPv2 in 3GPP TS 29.274 [3].
5.6	Restoration and Recovery 
This is performed as according to GTPv2 in 3GPP TS 23.007 [5].
6	Sv Information Elements
6.1	General
IE type value used in Sv Message is defined in TS 29.274 [3]. The IE format is coded as per GTP in TS 29.274 [3]. 
Table 6.1 shows the IEs used for SRVCC. Within information elements, certain fields may be described as spare. These bits shall be transmitted with the value set to 0. To allow for future features, the receiver shall not evaluate these bits.
Table 6.1-1: Information Elements for SRVCC 
IE Type value (Decimal)
Information elements
Comment / Reference
Number of Fixed Octets
0
Reserved
3GPP TS 29.274 [3]
3GPP TS 29.274 [3]
1
International Mobile Subscriber Identity (IMSI)
3GPP TS 29.274 [3]
3GPP TS 29.274 [3]
2
Cause
3GPP TS 29.274 [3]
3GPP TS 29.274 [3]
3
Recovery (Restart Counter)
3GPP TS 29.274 [3]
3GPP TS 29.274 [3]
4-50
Reserved for S101 interface
3GPP TS 29.274 [3]
3GPP TS 29.274 [3]
51
STN-SR
Variable Length / 6.2
Not Applicable
52
Source to Target Transparent Container
Variable Length / 6.3
Not Applicable
53
Target to Source Transparent Container
Variable Length / 6.4
Not Applicable
54
MM Context for E-UTRAN SRVCC
Variable Length / 6.5
Not Applicable
55
MM Context for UTRAN SRVCC
Variable Length / 6.6
Not Applicable
56
SRVCC Cause
Fixed Length / 6.7
1
57
Target RNC ID
Variable Length / 6.8
Not Applicable
58
Target Global Cell ID
Variable Length / 6.9
Not Applicable
59
TEID-C
Extendable / 6.10
4
60
Sv Flags
Extendable / 6.11
1
61
Service Area Identifier
Extendable / 6.12
7
62-70
For future Sv interface use
-

71-73
Reserved for GTPv2
3GPP TS 29.274 [3]
3GPP TS 29.274 [3]
74
IP Address
3GPP TS 29.274 [3]
3GPP TS 29.274 [3]
75
Mobile Equipment Identity (MEI)
3GPP TS 29.274 [3]
3GPP TS 29.274 [3]
76
MSISDN
3GPP TS 29.274 [3]
3GPP TS 29.274 [3]
77-254
Reserved for GTPv2
3GPP TS 29.274 [3]
3GPP TS 29.274 [3]
255
Private Extension
3GPP TS 29.274 [3]
3GPP TS 29.274 [3]
NOTE: 	The size of the TLI (Type, Length and Instance) fields, i.e "4" octets, has been subtracted from the number of the fixed octets of the "Fixed Length" and "Extendable" IEs.

6.2	STN-SR
STN-SR is defined in 3GPP TS 23.003 [4]. STN-SR is transferred via GTP tunnels. The sending entity copies the value part of the STN-SR into the Value field of the STN-SR IE. The STN-SR IE is coded as depicted in Figure 6.2-1. Octet 5 contains the Nature of Address and Numbering Plan Indicator (NANPI) of the "AddressString" ASN.1 type (see 3GPP TS 29.002 [11]). Octets 6 to (n+4) contain the actual STN-SR (digits of an address encoded as a TBCD-STRING as in the "AddressString" ASN.1 type). For an odd number of STN-SR digits, bits 8 to 5 of the last octet are encoded with the filler "1111". 


Bits

Octets87654321
1
Type = 51 (decimal)


2 to 3
Length = n


4
Spare
Instance


5
NANPI


6
Digit 2
Digit 1


…




n+4
Digit m
Digit (m-1)

Figure 6.2-1: STN-SR
6.3	Source to Target Transparent Container
The Source to Target Transparent Container contains information that shall be transferred transparently by CN entities from the source RAN to the target RAN. 
When the target network is GERAN,  the Transparent container field contains the value part of the Old BSS to New BSS Information IE defined in 3GPP TS 48.008 [8], i.e. octets 3 to n, excluding octet 1 (Element ID) and octet 2 (Length).
When the target network is UTRAN, this container carries the Source RNC to Target RNC Transparent Container IE defined in 3GPP TS 25.413 [9]. The Transparent container field contains a transparent copy of the corresponding ASN.1/PER IE. 
The receiver of this Information Element shall ignore the length of the transparent container encoded in octet 5 and shall derive the actual length of the container from the length encoded in octets 2 to 3 minus 1.  
For backward compatibility, the sender of this Information Element shall set the octet 5 to the actual length of the transparent container if the size of the container is smaller or equal to 255 octets, and to the value "255" otherwise.



Bits

Octets87654321
1
Type = 52 (decimal)


2 to 3
Length = n (decimal)


4
Spare
Instance


5
Length of the Transparent container


6 to (n+4)
Transparent container

Figure 6.3-1: Source to Target Transparent Container
6.4	Target to Source Transparent Container
The Target to Source Transparent Container contains information that shall be transferred transparently by CN entities from the target RAN to the source RAN. 
When the target network is GERAN, the Transparent container field contains the value part of the Layer 3 Information IE defined in 3GPP TS 48.008 [8], i.e., octets 3 to n, excluding octet 1 (Element ID) and octet 2 (Length).
When the target network is UTRAN, this container carries the Target RNC to Source RNC Transparent Container IE defined in 3GPP TS 25.413 [9]. The Transparent container field contains a transparent copy of the corresponding ASN.1/PER IE.
The receiver of this Information Element shall ignore the length of the transparent container encoded in octet 5 and shall derive the actual length of the container from the length encoded in octets 2 to 3 minus 1.
For backward compatibility, the sender of this Information Element shall set the octet 5 to the actual length of the transparent container if the size of the container is smaller or equal to 255 octets, and to the value "255" otherwise.



Bits

Octets87654321
1
Type = 53 (decimal)


2 to 3
Length = n


4
Spare
Instance


5
Length of the Transparent container


6 to (n+4)
Transparent container

Figure 6.4-1: Target to Source Transparent Container
6.5	MM Context for E-UTRAN SRVCC
The MM Context information element contains mobile station classmarks, supported codec list, and the security parameters that are necessary for the MSC server to setup the ciphering connection (and integrity protection for 3G) with the target access for SRVCC. CS ciphering keys parameters: CKSRVCC, IKSRVCC, and eKSI for E-UTRAN SRVCC are defined in 3GPP TS 33.401 [6]. 
Mobile Station Classmark 2, Mobile Station Classmark 3, and Supported Codec List information Elements indicate the supported encryption algorithms for GERAN access and CS supported codecs. The coding of Mobile Station Classmarks and Supported Codec List fields include the IE value part as it is specified in 3GPP TS 24.008 [7]. 
eKSI shall be coded as bits 1 to 3 of the NAS Key Set Identifier IE in TS 24.301 [12].For an emergency call without an authenticated IMSI, the source MME shall set the key sequence value of the eKSI to the value '111' and CKSRVCC and IKSRVCC to all 0’s in binary.



Bits

Octets87654321
1
Type = 54 (decimal)


2 to 3
Length = n


4
Spare
Instance


5
Spare
eKSI


6 to 21
CKSRVCC


22 to 37
IKSRVCC


38
Length of the Mobile Station Classmark 2


39 to a
Mobile Station Classmark 2


b
Length of the Mobile Station Classmark 3


(b+1) to c
Mobile Station Classmark 3


d
Length of the Supported Codec List


(d+1) to (n+4)
Supported Codec List

Figure 6.5-1: MM Context for E-UTRAN SRVCC
6.6	MM Context for UTRAN SRVCC
The MM Context information element contains mobile station classmarks, supported codec list, and the security parameters that are necessary for the MSC server to setup the ciphering connection (and integrity protection for 3G) with the target access for SRVCC. The usage of CK’CS, IK’CS, KSI’CS, Kc’, CKSN’CS are defined in 3GPP TS 33.102 [10].
Mobile Station Classmark 2, Mobile Station Classmark 3, and Supported Codec List information Elements indicate the supported encryption algorithms for GERAN access and CS supported codecs. The coding of Mobile Station Classmarks and Supported Codec List fields include the IE value part as it is specified in 3GPP TS 24.008 [7]. 
CKSN'cs shall be coded as bits 1 to 8 of the CKSN IE in TS 24.008 [7]. The KSI'cs shall be coded as bits 1 to 4 of the CKSN IE in TS 24.008 [7].
The source SGSN will send to the MSC Server enhanced for SRVCC either the KSI'cs/CK'cs/IK'cs for an UMTS subscriber or the CKSN'cs/Kc' for a GSM subscriber (see 3GPP TS 33.102 [10]): 
when transferring KSI'cs/CK'cs/IK'cs, the source SGSN shall set the key sequence value of the CKSN'cs to the value '111' and Kc’ to all 0’s in binary; 
when transferring CKSN'cs/Kc', the source SGSN shall set the key sequence value of the KSI’cs to the value '111', and CK’cs and IK’cs to all 0’s in binary. 
For an emergency call without an authenticated IMSI, the source SGSN shall set the key sequence value of the CKSN'cs and KSI'cs to all 1’s, and Kc’, CK’cs and IK’cs to all 0’s in binary.  



Bits

Octets87654321
1
Type = 55 (decimal)


2 to 3
Length = n


4
Spare
Instance


5
Spare
KSI’CS


6 to 21
CK’CS


22 to 37
IK’CS


38 to 45
Kc’


46
CKSN’CS


47
Length of the Mobile Station Classmark 2


48 to a
Mobile Station Classmark 2


b
Length of the Mobile Station Classmark 3


(b+1) to c
Mobile Station Classmark 3


d
Length of the Supported Codec List


(d+1) to (n+4)
Supported Codec List

Figure 6.6-1: MM Context for UTRAN SRVCC
6.7	SRVCC Cause
SRVCC Cause IE is coded as this is depicted in Figure 6.7-1.


Bits

Octets87654321
1
Type = 56 (decimal)


2 to 3
Length = 1


4
Spare
Instance


5
SRVCC Cause value

Figure 6.7-1: SRVCC Cause
The SRVCC Cause value indicates the reason for cancellation or the rejection of the SRVCC PS to CS Request. 
Table 6.7-1: SRVCC Cause values
Cause value 
(decimal)
Meaning
0
Reserved. Shall not be sent and if received the Cause shall be treated as an invalid IE
1
Unspecified
2
Handover/Relocation cancelled by source system 
3
Handover /Relocation Failure with Target system
4
Handover/Relocation Target not allowed
5
Unknown Target ID
6
Target Cell not available
7
No Radio Resources Available in Target Cell
8
Failure in Radio Interface Procedure
9-255
Spare. This value range is reserved for SRVCC Cause values

6.8	Target RNC ID 
This IE shall contain the identity of the target RNC. The encoding of this IE is defined in 3GPP TS 29.002 [11].


Bits

Octets87654321
1
Type = 57 (decimal)


2 to 3
Length = n (decimal)


4
Spare
Instance


5 to (n+4)
RNC ID

Figure 6.8-1: Target RNC ID
6.9	Target Global Cell ID 
This IE shall contain the identity of the target GSM Cell ID. The encoding of this IE is defined in 3GPP TS 29.002 [11].


Bits

Octets87654321
1
Type = 58 (decimal)


2 to 3
Length = n (decimal)


4
Spare
Instance


5 to (n+4)
Cell ID

Figure 6.9-1: Target Cell ID
6.10	Tunnel Endpoint Identifier for Control Plane (TEID-C)
Tunnel Endpoint Identifier for Control Plane (TEID-C) is coded as depicted in Figure 6.10-1.


Bits

Octets87654321
1
Type = 59 (decimal)


2-3
Length = n (decimal)


4
Spare
Instance


5-8
Tunnel Endpoint Identifier for Control Plane (TEID-C)


9-(n+4)
These octet(s) is/are present only if explicitly specified

Figure 6.10-1: Tunnel Endpoint Identifier for Control Plane (TEID-C)
6.11	Sv Flags
Sv Flags is coded as depicted in Figure 6.11-1.


Bits

Octets87654321
1
Type = 60 (decimal)


2 to 3
Length = n


4
Spare
Instance

5SpareSpareSpareSpareSpareSTIICSEmInd
6-(n+4)
These octet(s) is/are present only if explicitly specified

Figure 6.11-1: Sv Flags
The following bits within Octet 5 indicate:
-	Bit 1 – EmInd (Emergency Indicator): This flag is used to indicate the IMS emergency session. 
-	Bit 2 – ICS (IMS Centralized Service): This flag is used to request ICS support.
-	Bit 3 – STI (Session Transfer Indicator): This flag is used to indicate IMS session transfer has been invoked.
6.12	Service Area Identifier 
This IE shall contain the identifier of a service area. The encoding of this IE is defined in Figure 6.12-1.


Bits

Octets87654321
1
Type = 61 (decimal)


2-3
Length = n


4
Spare
Instance


5
MCC digit 2
MCC digit 1


6
MNC digit 3
MCC digit 3


7
MNC digit 2
MNC digit 1


8 to 9
Location Area Code (LAC)


10 to 11
Service Area Code (SAC)


12-(n+4)
These octet(s) is/are present only if explicitly specified

Figure 6.12-1: Service Area Identifier
The Location Area Code (LAC) consists of 2 octets. Bit 8 of Octet 8 is the most significant bit and bit 1 of Octet 9 the least significant bit. The coding of the location area code is the responsibility of each administration. Coding using full hexadecimal representation shall be used.
The Service Area Code (SAC) consists of 2 octets. Bit 8 of Octet 10 is the most significant bit and bit 1 of Octet 11 the least significant bit. The SAC is defined by the operator. See 3GPP TS 23.003 [4] subclause 12.5 for more information. 
Annex A (informative):
Change history
DateTSG #TSG DocCT4 DocCRRevCatSubject/CommentOldNew2008-12CT#42CP-080715V2.0.0 approved in CT#422.0.08.0.02009-03CT#43CP-090047C4-09091900013FFinalizing Sv spec8.0.08.1.02009-09CT#45CP-090544C4-0916550003Definition of TEID-C IE8.1.08.2.02009-09CT#45CP-090544C4-0918600004Cleanup of ENs2009-09CT#45CP-090544C4-09211700052HSPA security parameter alignment2009-09CT#45CP-090561C4-09193900062IMEI Changes for SRVCC8.2.09.0.02009-12CT#46CP-090777C4-09406800111MSISDN Correction9.0.09.1.02009-12CT#46CP-090825-00122Alignment with stage 2 for SRVCC HO cancellation procedure2010-03CT#47CP-100027C4-10004220015FTEID-C, IP Address and UDP Port handling on Sv interface9.1.09.2.0CP-100027C4-1004320018FIE type value correctionCP-100047C4-1004250016FIMSI IE presence corrections2010-06CT#48CP-100280C4-10153400201FSession continuity terminology is not correct9.2.09.3.02010-09CT#49CP-100457C4-10240900212FIMEI over the Sv Interface9.3.09.4.02010-12CT#50CP-100667C4-10328700231FMM Context for UTRAN SRVCC9.4.09.5.02011-03CT#51CP-110043C4-11037100271ALength of the Transparent container9.5.09.6.0CP-110052C4-11040300242FTarget to Source Transparent Container in the SRVCC PS to CS Response message2011-06CT#52CP-110363C4-11158600292FSource SAI during SRVCC HO from UTRAN to GERAN9.6.09.7.0CP-110355C4-11158700331AIE Type Extendable CorrectionsCP-110353C4-11164300363ASTN-SR encoding clarification2011-12CT#54CP-110779C4-1128470045ACoding of Source to Target Transparent Container9.7.09.8.0CP-110784C4-11252400412FHandling of Extendable IEs2014-06CT#64CP-140232C4-14120900704FTransparent container ambiguity9.8.09.9.0




















 STYLEREF ZA 3GPP TS 29.280 V9.9.0 (2014-06)
 PAGE 17
 STYLEREF ZGSM Release 9


3GPP