6 Sv Information Elements

29.2803GPP3GPP Sv interface (MME to MSC, and SGSN to MSC) for SRVCCEvolved Packet System (EPS)Release 17TS

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]

4-34

Reserved for S101 interface

3GPP TS 29.276 [17]

3GPP TS 29.276 [17]

35-50

Reserved for S121 interface

3GPP TS 29.276 [17]

3GPP TS 29.276 [17]

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 (v)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

MM Context for CS to PS SRVCC

Extendable / 6.13

42

63-70

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]

77-85

Reserved for GTPv2

3GPP TS 29.274 [3]

3GPP TS 29.274 [3]

86

ULI

3GPP TS 29.274 [3]

3GPP TS 29.274 [3]

111

P-TMSI

3GPP TS 29.274 [3]

3GPP TS 29.274 [3]

112

P-TMSI Signature

3GPP TS 29.274 [3]

3GPP TS 29.274 [3]

117

GUTI

3GPP TS 29.274 [3]

3GPP TS 29.274 [3]

120

PLMN ID

3GPP TS 29.274 [3]

3GPP TS 29.274 [3]

121

Target Identification

3GPP TS 29.274 [3]

3GPP TS 29.274 [3]

122-154

Reserved for GTPv2

3GPP TS 29.274 [3]

3GPP TS 29.274 [3]

155

Allocation/Retention Priority (ARP)

3GPP TS 29.274 [3]

3GPP TS 29.274 [3]

156-254

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

Octets

8

7

6

5

4

3

2

1

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 (see subclauses 8.2.2 and 8.48 in 3GPP TS 29.274 [3]).

When the target network is E-UTRAN, the container carries the Source eNB To Target eNB Transparent Container IE defined in 3GPP TS 36.413 [14]. The Transparent container field contains a transparent copy of the corresponding ASN.1/PER IE (see subclauses 8.2.2 and 8.48 in 3GPP TS 29.274 [3]).

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

Octets

8

7

6

5

4

3

2

1

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 (see subclauses 8.2.2 and 8.48 in 3GPP TS 29.274 [3]).

When the target network is E-UTRAN, the container carries the Target eNB To Source eNB Transparent Container IE defined in 3GPP TS 36.413 [14]. The Transparent container field contains a transparent copy of the corresponding ASN.1/PER IE (see subclauses 8.2.2 and 8.48 in 3GPP TS 29.274 [3]).

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

Octets

8

7

6

5

4

3

2

1

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 (v)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 (v)SRVCC. CS ciphering keys parameters: CKSRVCC, IKSRVCC, and eKSI for E-UTRAN (v)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

Octets

8

7

6

5

4

3

2

1

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 (v)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

Octets

8

7

6

5

4

3

2

1

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

Octets

8

7

6

5

4

3

2

1

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 or the SRVCC CS to PS Request. The SRVCC Cause is also used by the target MME/SGSN to indicate the reason for a failure in the SRVCC CS to PS Complete Notification message..

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

Permanent session leg establishment error

10

Temporary session leg establishment error

11-255

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

Octets

8

7

6

5

4

3

2

1

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

Octets

8

7

6

5

4

3

2

1

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

Octets

8

7

6

5

4

3

2

1

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

Octets

8

7

6

5

4

3

2

1

1

Type = 60 (decimal)

2 to 3

Length = n

4

Spare

Instance

5

Spare

Spare

Spare

Spare

VHO

STI

ICS

EmInd

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.

– Bit 4 – VHO (vSRVCC flag): This flag is used to indicate that the vSRVCC HO is requested by the MME.

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

Octets

8

7

6

5

4

3

2

1

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.

6.13 MM Context for CS to PS SRVCC

The MM Context for CS to PS SRVCC information element contains the security parameters that are necessary for the MME/SGSN to setup the ciphering connection and integrity protection with the target access for SRVCC. The usage of CK’PS, IK’PS, KSI’PS, Kc’PS, CKSN’PS are defined in 3GPP TS 33.102 [10].

Note: Kc’PS, is called GPRS Kc in 3GPP TS 33.102 [10].

CKSN’PS shall be coded as bits 1 to 8 of the CKSN IE in TS 24.008 [7]. The KSI’PS shall be coded as bits 1 to 4 of the CKSN IE in TS 24.008 [7].

The source MSC Server shall send to the MME/SGSN either the KSI’PS /CK’PS /IK’PS or the CKSN’PS /Kc’PS as specified in 3GPP TS 33.102 [10] and 3GPP TS 33.401[15]:

– when transferring KSI’PS /CK’PS /IK’PS, the source MSC Server shall set the key sequence value of the CKSN’PS to the value ‘111’ and Kc’PS to all 0’s in binary;

– when transferring CKSN’PS /Kc’PS, the source MSC Server shall set the key sequence value of the KSI’PS to the value ‘111’, and CK’PS and IK’PS to all 0’s in binary.

Bits

Octets

8

7

6

5

4

3

2

1

1

Type = 62 (decimal)

2 to 3

Length = n

4

Spare

Instance

5

Spare

Spare

Spare

KSI’PS

6 to 21

CK’PS

22 to 37

IK’PS

38 to 45

Kc’PS

46

CKSN’PS

47 – (n+4)

These octet(s) is/are present only if explicitly specified

Figure 6.13-1: MM Context for CS to PS SRVCC

Annex A (informative):
Change history

Change history

Date

Meeting

TDoc

CR

Rev

Cat

Subject/Comment

New version

2008-12

CT#42

CP-080715

V2.0.0 approved in CT#42

8.0.0

2009-03

CT#43

CP-090047

0001

3

F

Finalizing Sv spec

8.1.0

2009-09

CT#45

CP-090544

0003

Definition of TEID-C IE

8.2.0

2009-09

CT#45

CP-090544

0004

Cleanup of ENs

2009-09

CT#45

CP-090544

0005

2

HSPA security parameter alignment

2009-09

CT#45

CP-090561

0006

2

IMEI Changes for SRVCC

9.0.0

2009-12

CT#46

CP-090777

0011

1

MSISDN Correction

9.1.0

2009-12

CT#46

CP-090825

0012

2

Alignment with stage 2 for SRVCC HO cancellation procedure

2010-03

CT#47

CP-100027

0015

F

TEID-C, IP Address and UDP Port handling on Sv interface

9.2.0

CP-100027

0018

F

IE type value correction

CP-100047

0016

F

IMSI IE presence corrections

2010-06

CT#48

CP-100280

0020

1

F

Session continuity terminology is not correct

9.3.0

2010-09

CT#49

CP-100457

0021

2

F

IMEI over the Sv Interface

9.4.0

2010-12

CT#50

CP-100667

0023

1

F

MM Context for UTRAN SRVCC

9.5.0

2011-03

CT#51

CP-110043

0027

1

A

Length of the Transparent container

9.6.0

CP-110052

0024

2

F

Target to Source Transparent Container in the SRVCC PS to CS Response message

2011-03

Update to Rel-10 version (MCC)

10.0.0

2011-06

CT#52

CP-110363

0031

1

A

Source SAI during SRVCC HO from UTRAN to GERAN

10.1.0

2011-06

CT#52

CP-110355

0034

1

A

IE Type Extendable Corrections

10.1.0

2011-06

CT#52

CP-110353

0037

3

A

STN-SR encoding clarification

10.1.0

2011-09

CT#53

CP-110565

0038

2

F

"MME/SGSN Sv Address for Control Plane" IE in SRVCC PS to CS Request

10.2.0

2011-09

CT#53

CP-110584

0039

2

B

Add vSRVCC updates to the Sv interface

11.0.0

2011-12

CT#54

CP-110779

0047

A

Coding of Source to Target Transparent Container

11.1.0

CP-110817

0040

1

B

eMPS for SRVCC

CP-110784

0043

2

A

Handing of Extendable IEs

2012-06

CT#56

CP-120234

0050

2

B

CS to PS SRVCC

11.2.0

CP-120227

0049

3

A

SRVCC cause values

CP-120229

0052

B

eMPS on vSRVCC

CP-120229

0053

2

F

Usage of messages for vSRVCC

2012-09

CT#57

CP-120475

0055

1

B

CS to PS SRVCC Cancel Notification/Acknowledge

11.3.0

CP-120475

0056

1

B

Remove NONCE in CS to PS SRVCC

CP-120475

0058

3

B

Anchor PLMN in SRVCC PS to CS Request

CP-120457

0059

F

Sv Flags clarifications

2013-06

CT#60

CP-130286

0060

3

F

MEI over Sv for Emergency Call

11.4.0

2013-09

CT#61

CP-130451

0061

F

GTP-C message types for rSRVCC

11.5.0

2013-09

CT#61

CP-130470

0062

1

B

Update to cover the S121

12.0.0

2013-12

CT#62

CP-130628

0063

1

F

Clarification on the encoding of Transparent Container

12.1.0

2014-06

CT#64

CP-140261

0069

1

F

Version Not Supported Indication

12.2.0

CP-140232

0073

4

Transparent container ambiguity

2015-03

CT#67

CP-150025

0074

F

Correct the wrong reference

12.3.0

CP-150025

0075

1

F

Usage of the GTPv2-C Header in Sv interface

12.3.0

2015-12

CT#70

Update to Rel-13 version (MCC)

13.0.0

2017-03

CT#75

Update to Rel-14 version (MCC)

14.0.0

2018-06

CT#80

Update to Rel-15 version (MCC)

15.0.0

2020-07

CT#88e

Update to Rel-16 version (MCC)

16.0.0

2022-04

Update to Rel-17 version (MCC)

17.0.0