5 Sv Messages and Information Elements
29.2803GPP3GPP Sv interface (MME to MSC, and SGSN to MSC) for SRVCCEvolved Packet System (EPS)Release 17TS
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 shall be conformant to the GTPv2-C Message Header, see 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 Messages are used for both the Inter-RAT handover from IMS based voice service over EPS to CS domain over 3GPP UTRAN/GERAN access or from UTRAN (HSPA) to 3GPP UTRAN/GERAN access and the Inter-RAT handover from IMS based voice and video service over EPS to CS domain over 3GPP UTRAN access.
Sv Messages are also used for the Inter-RAT handover from voice service in CS domain over 3GPP UTRAN/GERAN access to IMS based service over LTE or UTRAN (HSPA).
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 |
Initial |
Triggered |
|---|---|---|---|---|
|
0 |
Reserved |
3GPP TS 29.274 [3] |
||
|
1 |
Echo Request |
3GPP TS 29.274 [3] |
X |
|
|
2 |
Echo Response |
3GPP TS 29.274 [3] |
X |
|
|
3 |
Version Not Supported Indication |
3GPP TS 29.274 [3] |
X |
|
|
4-16 |
Reserved for S101 interface |
3GPP TS 29.276 [17] |
||
|
17-24 |
Reserved for S121 interface |
3GPP TS 29.276 [17] |
||
|
25 |
SRVCC PS to CS Request |
5.2.2 |
X |
|
|
26 |
SRVCC PS to CS Response |
5.2.3 |
X |
|
|
27 |
SRVCC PS to CS Complete Notification |
5.2.4 |
X |
|
|
28 |
SRVCC PS to CS Complete Acknowledge |
5.2.5 |
X |
|
|
29 |
SRVCC PS to CS Cancel Notification |
5.2.6 |
X |
|
|
30 |
SRVCC PS to CS Cancel Acknowledge |
5.2.7 |
X |
|
|
31 |
SRVCC CS to PS Request |
5.2.8 |
X |
|
|
32-239 |
Reserved for GTPv2 |
3GPP TS 29.274 [3] |
||
|
240 |
SRVCC CS to PS Response |
5.2.9 |
X |
|
|
241 |
SRVCC CS to PS Complete Notification |
5.2.10 |
X |
|
|
242 |
SRVCC CS to PS Complete Acknowledge |
5.2.11 |
X |
|
|
243 |
SRVCC CS to PS Cancel Notification |
5.2.12 |
X |
|
|
244 |
SRVCC CS to PS Cancel Acknowledge |
5.2.13 |
X |
|
|
245 to 247 |
For future Sv interface use |
– |
||
|
248-255 |
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 and in the SRVCC CS to PS Request message header shall be set to "0" because this is the first message sent between the MME/SGSN and 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.
The TEID field in the SRVCC CS to PS Cancel Notification message header shall be set to "0" if the message is sent before reception of the acceptance response to the SRVCC CS to PS Request. If the MSC Server sends the SRVCC CS to PS Cancel Notification message after the acceptance response to the SRVCC CS to PS Request, the TEID field of the SRVCC CS to PS Cancel Notification message may be set to the MME/SGSN TEID value received in the SRVCC CS to PS Response message. Therefore the MME/SGSN shall be able to accept the SRVCC CS to PS 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].
This message shall also be sent across Sv interface from the MME to the target MSC server as part of the vSRVCC 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 all types of emergency calls by the MME and the SGSN. |
MEI |
0 |
|
CO |
This IE shall be included for all SRVCC calls if available in the MME or SGSN (NOTE 2). |
|||
|
Sv Flags |
C |
This IE shall be included if any one of the applicable flags is set to 1. 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. – VHO: this flag shall be sent if the MME requests the vSRVCC HO. |
Sv Flags |
0 |
|
MME/SGSN Sv Address for Control Plane |
M |
This IE specifies the address for control plane Initial message which is chosen by the source MME/SGSN. The target MSC Server shall send subsequent control plane Initial messages related to the GTP tunnel for this UE towards this address. |
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 MSC Server shall include this TEID in the GTP header of all control plane messages related to the GTP tunnel for this UE. |
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 (v)SRVCC |
C |
The MME shall include mobile station classmarks, supported codecs, and CS Security key in MM Context for E-UTRAN (v)SRVCC. The derivation of the CS security keys shall follow the procedures defined 3GPP TS 33.401[7]. |
MM Context for E-UTRAN (v)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 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 (v)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 |
|
Allocation/Retention Priority |
CO |
The MME shall include this IE if (v)SRVCC with priority is supported and (v)SRVCC is performed for an IMS-based MPS session (see 3GPP TS 23.216 [2]). |
ARP |
0 |
|
Anchor PLMN ID |
CO |
The MME/SGSN shall include this IE during SRVCC from UTRAN/E-UTRAN PS to UTRAN/GERAN CS domain GWCN/MOCN to be used for subsequent SRVCC handover in the reverse direction as specified in 3GPP TS 23.251 [16]. |
PLMN ID |
0 |
|
Private Extension |
O |
None |
Private Extension |
VS |
|
NOTE1: Based upon the SRVCC Handover procedure, either Target RNC ID or Target Cell ID shall be present in this message NOTE2: 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 |
|
|
(v)SRVCC rejected Cause |
CO |
This IE shall be sent if Cause value differs from "Request accepted". MSC Server shall include this information element 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 during SRVCC procedure as specified in 3GPP TS 23.216 [2]:
– to indicate the SRVCC handover with CS Domain has been successfully finished;
– or to indicate the SRVCC handover with CS Domain has finished (i.e. HO Complete / Relocation Complete message has been received from the target RAN) but the IMS Session Transfer procedure completion in 3GPP TS 23.237 [13] has failed by including the appropriate SRVCC post failure Cause value.
This message shall also be sent on Sv interface to the source MME during vSRVCC 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 |
|
SRVCC post failure Cause |
CO |
This IE shall be sent if a call is to be released locally in the MSC Server due to IMS session leg establishment failure. The MSC Server shall include this IE to indicate the nature of the failure (i.e, permanent or temporary) |
SRVCC Cause |
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 (v)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.
This message shall also be sent across Sv interface from the MME to the target MSC server to request the cancellation of an ongoing vSRVCC 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 |
This IE shall be included if any one of the applicable flags is set to 1. 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 |
5.2.8 SRVCC CS to PS Request
A SRVCC CS to PS Request message shall be sent across Sv interface from the MSC Server to the target MME/SGSN as part of UTRAN/GERAN to E-UTRAN/UTRAN (HSPA) SRVCC procedure in 3GPP TS 23.216 [2].
Table 5.28 specifies the presence requirements and conditions of the IEs in the message.
Table 5.2.8: Information Elements in a SRVCC CS to PS Request
|
Information elements |
P |
Condition / Comment |
IE Type |
Ins. |
|
IMSI |
C |
The IE shall be included if available. |
IMSI |
0 |
|
ME Identity (MEI) |
C |
This IE shall be included if available. |
MEI |
0 |
|
MSC Server Sv Address for Control Plane |
M |
This IE specifies the address for control plane Initial message which is chosen by the source MSC Server. The target MME/SGSN shall send subsequent control plane Initial messages related to the GTP tunnel for this UE towards this address. |
IP Address |
0 |
|
MSC Server Sv TEID for Control Plane |
M |
This IE specifies the tunnel for control plane message which is chosen by the source MSC Server. The target MME/SGSN shall include this TEID in the GTP header of all control plane messages related to the GTP tunnel for this UE. |
TEID-C |
0 |
|
Source to Target Transparent Container |
M |
The MSC Server shall include Source to Target Transparent Container IE. |
Source to Target Transparent Container |
0 |
|
Target Identification |
M |
This IE shall be included to identify the target access. |
Target Identification |
0 |
|
P-TMSI |
C |
This IE shall be included if available. |
P-TMSI |
0 |
|
Source RAI |
C |
This IE shall be included if available |
ULI |
0 |
|
P-TMSI Signature |
C |
This IE shall be included if available |
P-TMSI Signature |
0 |
|
GUTI |
C |
This IE shall be included if available. |
GUTI |
0 |
|
MM Context for CS to PS SRVCC |
M |
MM Context for CS to PS SRVCC |
0 |
|
|
Private Extension |
O |
None |
Private Extension |
VS |
5.2.9 SRVCC CS to PS Response
A SRVCC CS to PS Response message shall be sent across Sv interface as a response to SRVCC CS to PS Request by the MME/SGSN during UTRAN/GERAN to E-UTRAN/UTRAN (HSPA) SRVCC procedure as specified in 3GPP TS 23.216 [2].
Table 5.2.9 specifies the presence requirements and conditions of the IEs in the message.
Cause IE indicates if the SRVCC CS to PS request has been accepted, or not. The request has not been accepted by the target MME/SGSN if the Cause IE value differs from "Request accepted".
Table 5.2.9: Information Elements in a SRVCC CS to PS 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". MME/SGSN may include additional information to indicate the reason for rejecting SRVCC CS to PS request |
SRVCC Cause |
0 |
|
MME/SGSN Sv Address for Control Plane |
O |
If the Cause IE contains the value" Request accepted", the target MME/SGSN may include MME/SGSN Sv Address for Control Plane IE in SRVCC CS to PS Response message if target MME/SGSN decides to use different IP address for the subsequent communication. The source MSC Server shall store this MME/SGSN address and use it when sending subsequent control plane initial messages to this GTP-C tunnel. |
IP Address |
0 |
|
MME/SGSN Sv TEID for Control Plane |
C |
The target MME/SGSN shall include MME/SGSN Sv Tunnel Endpoint Identifier for Control Plane IE in SRVCC CS to PS Response message if the Cause IE contains the value "Request accepted". The source MSC Server shall include this TEID-C in the GTP-C header of all subsequent control plane messages from the source MSC Server to the target MME/SGSN. |
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 Transparent Container |
0 |
|
Private Extension |
O |
None |
Private Extension |
VS |
5.2.10 SRVCC CS to PS Complete Notification
A SRVCC CS to PS Complete Notification message shall be sent across Sv interface from the target MME/SGSN to the source MSC Server to indicate the SRVCC handover with PS Domain has been finished during UTRAN/GERAN to E-UTRAN/UTRAN (HSPA) SRVCC procedure as specified in 3GPP TS 23.216 [2].
Table 5.2.10 specifies the presence requirements and conditions of the IEs in the message.
Table 5.2.10: Information Elements in a SRVCC CS to PS Complete Notification
|
Information elements |
P |
Condition / Comment |
IE Type |
Ins. |
|
SRVCC failure Cause |
C |
This IE shall be included if there is a failure detected by the target MME/SGSN during UTRAN/GERAN to E-UTRAN/UTRAN (HSPA) SRVCC procedure as specified in 3GPP TS 23.216 [2]. |
SRVCC cause |
0 |
|
Private Extension |
O |
None |
Private Extension |
VS |
5.2.11 SRVCC CS to PS Complete Acknowledge
A SRVCC CS to PS Complete Acknowledge message shall be sent across Sv interface as a response to SRVCC CS to PS Complete Notification during UTRAN/GERAN to E-UTRAN/UTRAN (HSPA) SRVCC procedure as specified in 3GPP TS 23.216 [2].
Table 5.2.10 specifies the presence requirements and conditions of the IEs in the message.
Table 5.2.11: Information Elements in a SRVCC CS to PS Complete Acknowledge
|
Information elements |
P |
Condition / Comment |
IE Type |
Ins. |
|
Cause |
M |
None |
Cause |
0 |
|
Private Extension |
O |
None |
Private Extension |
VS |
5.2.12 SRVCC CS to PS Cancel Notification
A SRVCC CS to PS Cancel Notification message shall be sent across Sv interface from the MSC Server to the target MME/SGSN to request the cancellation of an ongoing SRVCC handover.
Table 5.2.12 specifies the presence requirements and conditions of the IEs in the message.
Table 5.2.12: Information Elements in a SRVCC CS to PS Cancel Notification
|
Information elements |
P |
Condition / Comment |
IE Type |
Ins. |
|
IMSI |
C |
The IMSI shall be included if available. |
IMSI |
0 |
|
Cancel Cause |
M |
MSC Server shall indicate the reason for Handover cancellation. |
SRVCC Cause |
0 |
|
ME Identity (MEI) |
C |
This IE shall be included if available. |
MEI |
0 |
|
Private Extension |
O |
None |
Private Extension |
VS |
5.2.13 SRVCC CS to PS Cancel Acknowledge
A SRVCC CS to PS Cancel Acknowledge message shall be sent across Sv interface as a response to SRVCC CS to PS Cancel Notification.
Table 5.2.13 specifies the presence requirements and conditions of the IEs in the message.
Table 5.2.13: Information Elements in a SRVCC CS to PS Cancel Acknowledge
|
Information elements |
P |
Condition / Comment |
IE Type |
Ins. |
|
Cause |
M |
None |
Cause |
0 |
|
Private Extension |
O |
None |
Private Extension |
VS |
5.3 Path Management Messages
5.3.1 Introduction
The following GTPv2-C messages support path management for the Sv interface:
– Echo Request
– Echo Response
– Version Not Supported Indication
These messages are defined for GTPv2-C and the handling and definition shall also be as defined in GTPv2-C, see 3GPP TS 29.274 [3].
5.3.2 Echo Request message
3GPP TS 29.274 [3] 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 Indication message
3GPP TS 29.274 [3] specifies the detailed handling and information elements included in the Version Not Supported Indication 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].