18 Message format and information element coding

09.183GPPGeneral Packet Radio Service (GPRS)Gs interface layer 3 specificationServing GPRS Support Node (SGSN) - Visitors Location Register (VLR)TS

This clause specifies the coding of the Information Elements used in by the BSSAP+ protocol. The spare bits in the coding of an IE shall be set to zero by the sender and shall be ignored by the receiver.

All unassigned codes (whether omitted or explicitely Unassigned in the text) shall be treated as unknown (see clause ‘Error Handling and Future Compatibility’).

18.1 Overview

18.2 Message type

Message type uniquely identifies the message being sent. It is a single octet element, mandatory in all messages.

Table 18.2/3GPP TS 09.18: Message type information element

8 7 6 5 4 3 2 1

Message type

Reference

0 0 0 0 0 0 0 0

Unassigned: treated as an unknown Message type.

18&16

0 0 0 0 0 0 0 1

BSSAP+-PAGING-REQUEST

17.1.18

0 0 0 0 0 0 1 0

BSSAP+-PAGING-REJECT

17.1.17

0 0 0 0 0 0 1 1

to

0 0 0 0 1 0 0 0

Unassigned: treated as an unknown Message type.

18&16

0 0 0 0 1 0 0 1

BSSAP+-LOCATION-UPDATE-REQUEST

17.1.10

0 0 0 0 1 0 1 0

BSSAP+-LOCATION-UPDATE-ACCEPT

17.1.8

0 0 0 0 1 0 1 1

BSSAP+-LOCATION-UPDATE-REJECT

17.1.9

0 0 0 0 1 1 0 0

BSSAP+-TMSI-REALLOCATION-COMPLETE

17.1.21

0 0 0 0 1 1 0 1

BSSAP+-ALERT-REQUEST

17.1.3

0 0 0 0 1 1 1 0

BSSAP+-ALERT-ACK

17.1.1

0 0 0 0 1 1 1 1

BSSAP+-ALERT-REJECT

17.1.2

0 0 0 1 0 0 0 0

BSSAP+-MS-ACTIVITY-INDICATION

17.1.13

0 0 0 1 0 0 0 1

BSSAP+-GPRS-DETACH-INDICATION

17.1.5

0 0 0 1 0 0 1 0

BSSAP+-GPRS-DETACH-ACK

17.1.4

0 0 0 1 0 0 1 1

BSSAP+-IMSI-DETACH-INDICATION

17.1.7

0 0 0 1 0 1 0 0

BSSAP+-IMSI-DETACH-ACK

17.1.6

0 0 0 1 0 1 0 1

BSSAP+-RESET-INDICATION

17.1.20

0 0 0 1 0 1 1 0

BSSAP+-RESET-ACK

17.1.19

0 0 0 1 0 1 1 1

BSSAP+-MS-INFORMATION-REQUEST

17.1.14

0 0 0 1 1 0 0 0

BSSAP+-MS-INFORMATION-RESPONSE

17.1.15

0 0 0 1 1 0 0 1

Unassigned: treated as an unknown Message type.

18&16

0 0 0 1 1 0 1 0

BSSAP+-MM-INFORMATION-REQUEST

17.1.11

0 0 0 1 1 1 0 1

BSSAP+-MOBILE-STATUS

17.1.12

0 0 0 1 1 1 1 0

Unassigned: treated as an unknown Message type.

18&16

0 0 0 1 1 1 1 1

BSSAP+-MS-UNREACHABLE

17.1.16

18.3 Information Element Identifiers

The next list shows the coding of the Information Element Identifiers used in the present document.

Table 18.3/3GPP TS 09.18: Information Element Identifier coding

8 7 6 5 4 3 2 1

Information element

Reference

0 0 0 0 0 0 0 1

IMSI

18.4.9

0 0 0 0 0 0 1 0

VLR number

18.4.24

0 0 0 0 0 0 1 1

TMSI

18.4.22

0 0 0 0 0 1 0 0

Location area identifier

18.4.13

0 0 0 0 0 1 0 1

Channel Needed

18.4.2

0 0 0 0 0 1 1 0

eMLPP Priority

18.4.3

0 0 0 0 0 1 1 1

TMSI status

18.4.23

0 0 0 0 1 0 0 0

Gs cause

18.4.6

0 0 0 0 1 0 0 1

SGSN number

18.4.21

0 0 0 0 1 0 1 0

GPRS location update type

18.4.5

0 0 0 0 1 0 1 1

Unassigned: treated as an unknown IEI.

18&16

0 0 0 0 1 1 0 0

Unassigned: treated as an unknown IEI.

18&16

0 0 0 0 1 1 0 1

Mobile station classmark 1

18.4.17

0 0 0 0 1 1 1 0

Mobile identity

18.4.16

0 0 0 0 1 1 1 1

Reject cause

18.4.20

0 0 0 1 0 0 0 0

IMSI detach from GPRS service type

18.4.10

0 0 0 1 0 0 0 1

IMSI detach from non-GPRS service type

18.4.11

0 0 0 1 0 0 1 0

Information requested

18.4.12

0 0 0 1 0 0 1 1

PTMSI

18.4.19

0 0 0 1 0 1 0 0

IMEI

18.4.7

0 0 0 1 0 1 0 1

IMEISV

18.4.8

0 0 0 1 0 1 1 0

Unassigned: treated as an unknown IEI.

18&16

0 0 0 1 0 1 1 1

MM information

18.4.15

0 0 0 1 1 0 0 0

Cell Global Identity

18.4.1

0 0 0 1 1 0 0 1

Location information age

18.4.14

0 0 0 1 1 0 1 0

Mobile station state

18.4.18

0 0 0 1 1 0 1 1

Erroneous message

18.4.4

0 0 0 1 1 1 0 0

to

1 1 1 1 1 1 1 1

Unassigned: treated as an unknown IEI.

18&16

18.4 Information elements

18.4.1 Cell global identity

This information element uniquely identifies one cell.

8

7

6

5

4

3

2

1

Octet 1

IEI

Octet 2

Length indicator

Octet 3

to

Octet 10

The rest of the information element is coded as the the value part of the cell global id IE defined in 3GPP TS 08.18 (not including 3GPP TS 08.18 IEI and 3GPP TS 08.18 length indicator).

Figure 18.4.1/3GPP TS 09.18: Cell global identity IE

18.4.2 Channel needed

The purpose of the Channel Needed information element is to indicate which type of channel is needed for the transaction linked to the paging procedure.

8

7

6

5

4

3

2

1

Octet 1

IEI

Octet 2

Length indicator

Octet 3

The rest of the information element is coded as the IEI part and the value part of the Channel Needed IE defined in 3GPP TS 04.08.

Figure 18.4.2/3GPP TS 09.18: Channel needed IE

18.4.3 eMLPP Priority

This element indicates the eMLPP-Priority.

8

7

6

5

4

3

2

1

Octet 1

IEI

Octet 2

Length indicator

Octet 3

The rest of the information element is coded as the value part of the eMLPP-Priority IE defined in 3GPP TS 08.08 (not including 3GPP TS 08.08 IEI and 3GPP TS 08.08 length indicator).

Figure 18.4.3/3GPP TS 09.18: eMLPP Priority IE

18.4.4 Erroneous message

The Erroneous message IE is a TLV IE that encapsulates the message in error.

8

7

6

5

4

3

2

1

Octet 1

IEI

Octet 2

Length indicator

Octet 3

Octet n

Erroneous message including the message type.

Figure 18.4.4/3GPP TS 09.18: Erroneous message IE

18.4.5 GPRS location update type

The purpose of the GPRS location update type information element is to indicate to the VLR whether an IMSI attach or a normal location update has been performed by the MS.

8

7

6

5

4

3

2

1

Octet 1

IEI

Octet 2

Length indicator

Octet 3

GPRS location update type value

Figure 18.4.5/3GPP TS 09.18: GPRS location update type IE

Table 18.4.5/3GPP TS 09.18: GPRS location update type IE value part

GPRS location update type value (octet 3)

Bits

8 7 6 5 4 3 2 1

0 0 0 0 0 0 0 0 Shall not be sent in this version of the protocol. If received, shall be treated as ‘00000010’.

0 0 0 0 0 0 0 1 IMSI attach

0 0 0 0 0 0 1 0 Normal location update

0 0 0 0 0 0 1 1 Shall not be sent in this version of the protocol. If received, to shall be treated as 00000010’.

to

1 1 1 1 1 1 1 1

18.4.6 Gs cause

The purpose of the value part of the Gs Cause information element is to indicate an error to the receiving entity. This could be a protocol data error or to indicate to the VLR the reason why a paging procedure could not be performed.

8

7

6

5

4

3

2

1

Octet 1

IEI

Octet 2

Length indicator

Octet 3

Gs Cause value

Figure 18.4.6/3GPP TS 09.18: Gs Cause IE

Table 18.4.6/3GPP TS 09.18: Gs Cause IE value part

Gs Cause value (octet 3)

Bits

8 7 6 5 4 3 2 1

0 0 0 0 0 0 0 0 Normal, unspecified in this version of the protocol.

0 0 0 0 0 0 0 1 IMSI detached for GPRS services

0 0 0 0 0 0 1 0 IMSI detached for GPRS and non-GPRS services

0 0 0 0 0 0 1 1 IMSI unknown

0 0 0 0 0 1 0 0 IMSI detached for non-GPRS services

0 0 0 0 0 1 0 1 IMSI implicitly detached for non-GPRS services

0 0 0 0 0 1 1 0 MS unreachable

0 0 0 0 0 1 1 1 Message not compatible with the protocol state

0 0 0 0 1 0 0 0 Missing mandatory information element

0 0 0 0 1 0 0 1 Invalid mandatory information

0 0 0 0 1 0 1 0 Conditional IE error

0 0 0 0 1 0 1 1 Semantically incorrect message

0 0 0 0 1 1 0 0 Message unknown

0 0 0 0 1 1 0 1 Address error

0 0 0 0 1 1 1 0

to Normal, unspecified in this version of the protocol 1 1 1 1 1 1 1 1

NOTE: ‘Normal, unspecified’ has the same meaning than in 3GPP TS 04.08, informative Annex H (GSM specific cause values for call control). It is used to report a normal event, and should not be interpreted as syntactically incorrect nor unknown if received.

18.4.7 IMEI

The IMEI is coded as a sequence of BCD digits, compressed two into each octet. The IMEI consists of 15 digits (see 3GPP TS 03.03).

8

7

6

5

4

3

2

1

octet 1

IEI

octet 2

length indicator

octet 3

TAC digit 2

TAC digit 1

octet 4

TAC digit 4

TAC digit 3

octet 5

TAC digit 6

TAC digit 5

octet 6

FAC digit 2

FAC digit 1

octet 7

SNR digit 2

SNR digit 1

octet 8

SNR digit 4

SNR digit 3

octet 9

SNR digit 6

SNR digit 5

octet 10

1

1

1

1

0

0

0

0

Figure 18.4.7/3GPP TS 09.18: IMEI IE

18.4.8 IMEISV

The IMEISV is coded as a sequence of BCD digits, compressed two into each octet. The IMEISV consists of 16 digits (see 3GPP TS 03.03).

8

7

6

5

4

3

2

1

octet 1

IEI

octet 2

length indicator

octet 3

TAC digit 2

TAC digit 1

octet 4

TAC digit 4

TAC digit 3

octet 5

TAC digit 6

TAC digit 5

octet 6

FAC digit 2

FAC digit 1

octet 7

SNR digit 2

SNR digit 1

octet 8

SNR digit 4

SNR digit 3

octet 9

SNR digit 6

SNR digit 5

octet 10

SVN digit 2

SVN digit 1

Figure 18.4.8/3GPP TS 09.18: IMEISV IE

18.4.9 IMSI

The IMSI is coded as a sequence of BCD digits, compressed two into each octet. This is a variable length element, and includes a length indicator. The IMSI is defined in 3GPP TS 03.03. It shall not exceed 15 digits (see 3GPP TS 03.03).

8

7

6

5

4

3

2

1

Octet 1

IEI

Octet 2

Length indicator

Octet 3

IMSI digit 1

* parity

0

0

1

Octet 4

IMSI digit 3

IMSI digit 2

Octet 4+x

IMSI digit i+1

IMSI digit i

Figure 18.4.9/3GPP TS 09.18: IMSI IE

Where x = (i-2)/2 and i is always even

* The value of the parity bit (bit 4 in octect 3) indicates:

0 Even number of IMSI digits

1 Odd number of IMSI digits

If the number of IMSI digits is even then bits 5 to 8 of the last octet shall be filled with an end mark coded as 1111.

18.4.10 IMSI detach from GPRS service type

The purpose of the IMSI detach from GPRS service type information element is to indicate to the VLR the type of IMSI detach from GPRS service performed by the MS or the SGSN.

8

7

6

5

4

3

2

1

Octet 1

IEI

Octet 2

Length indicator

Octet 3

IMSI detach from GPRS service type value

Figure 18.4.10/3GPP TS 09.18: IMSI detach from GPRS service type IE

Table 18.4.10/3GPP TS 09.18: IMSI detach from GPRS service type IE value part

IMSI detach from GPRS service type value (octet 3)

Bits

8 7 6 5 4 3 2 1

0 0 0 0 0 0 0 0 Interpreted as reserved in this version of the protocol 0 0 0 0 0 0 0 1 Network initiated IMSI detach from GPRS service

0 0 0 0 0 0 1 0 MS initiated IMSI detach from GPRS service

0 0 0 0 0 0 1 1 GPRS services not allowed

0 0 0 0 0 1 0 0

to Interpreted as reserved in this version of the protocol

1 1 1 1 1 1 1 1

18.4.11 IMSI detach from non-GPRS service type

The purpose of the IMSI detach from non-GPRS service type information element is to indicate to the VLR if the type of IMSI detach from non-GPRS service was explicitly performed by the MS or implicitly performed by the SGSN.

8

7

6

5

4

3

2

1

Octet 1

IEI

Octet 2

Length indicator

Octet 3

IMSI detach from non-GPRS service type value

Figure 18.4.11/3GPP TS 09.18: IMSI detach from non-GPRS service type IE

Table 18.4.11/3GPP TS 09.18: IMSI detach from non-GPRS service type IE value part

IMSI detach from non-GPRS service type value (octet 3)

Bits

8 7 6 5 4 3 2 1

0 0 0 0 0 0 0 0 Interpreted as reserved in this version of the protocol

0 0 0 0 0 0 0 1 Explicit MS initiated IMSI detach from non-GPRS service

0 0 0 0 0 0 1 0 Combined explicit MS initiated IMSI detach from GPRS and non-GPRS services

0 0 0 0 0 0 1 1 Implicit SGSN initiated IMSI detach from non-GPRS service

0 0 0 0 0 1 0 0

to Interpreted as reserved in this version of the protocol

1 1 1 1 1 1 1 1

18.4.12 Information requested

The Information requested IE is a TLV IE that indicates to the SGSN the type of information requested by the VLR. The coding of the V field is as follows.

8

7

6

5

4

3

2

1

Octet 1

IEI

Octet 2

Length indicator

Octet 3

Information requested value

Figure 18.4.12/3GPP TS 09.18: Information requested IE

Table 18.4.12/3GPP TS 09.18: Information requested IE value part

Information requested value (octet 3)

Bits

8 7 6 5 4 3 2 1

0 0 0 0 0 0 0 0 Interpreted as Not supported in this version of the protocol.

0 0 0 0 0 0 0 1 PTMSI

0 0 0 0 0 0 1 0 IMEI

0 0 0 0 0 0 1 1 IMEISV

0 0 0 0 0 1 0 0 PTMSI and IMEI

0 0 0 0 0 1 0 1 PTMSI and IMEISV

0 0 0 0 0 1 1 0 IMEI and IMEISV

0 0 0 0 0 1 1 1 PTMSI, IMEI, and IMEISV

0 0 0 0 1 0 0 0 Mobile location information

0 0 0 0 1 0 0 1 TMSI

0 0 0 0 1 0 1 0 Interpreted as Not supported in this version of the protocol.

to

1 1 1 1 1 1 1 1

NOTE: The behaviour of the receiver in the case of a Not supported value is described in Sub-clause 14.3, Procedures in the SGSN.

18.4.13 Location area identifier

This element uniquely identifies one Location Area.

8

7

6

5

4

3

2

1

Octet 1

IEI

Octet 2

Length Indicator

Octet 3

Octer 7

The rest of the information element is coded as the value part of the location area identifier IE defined in 3GPP TS 08.18 (not including 3GPP TS 08.18 IEI and 3GPP TS 08.18 length indicator).

Figure 18.4.13/3GPP TS 09.18: Location area identifier IE

18.4.14 Location information age

The Location information age IE is a TLV IE that indicates the elapsed time in minutes since the last network contact of the mobile station.

8

7

6

5

4

3

2

1

Octet 1

IEI

Octet 2

Length indicator

Octet 3Octet 4

The rest of the IE is coded as the value part of the AgeOfLocationInformation as specified in 3GPP TS 09.02.

Figure 18.4.14/3GPP TS 09.18: Location information age IE

18.4.15 MM information

The MM information IE is a TLV IE that encapsulates the user information that the SGSN forwards to the MS.

8

7

6

5

4

3

2

1

Octet 1

IEI

Octet 2

Length Indicator

Octet 3

Octet n

User information: This field is composed of one or more of the information elements of the MM information message as defined in 3GPP TS 04.08, excluding the Protocol discriminator, Skip indicator and Message type. This field includes the IEI and length indicatior of the other information elements.

Figure 18.4.15/3GPP TS 09.18: MM information IE

18.4.16 Mobile identity

The purpose of the Mobile identity information element is to provide either:

– The International Mobile Subscriber Identity (IMSI) ;

– The Temporary Mobile Subscriber Identity (TMSI) ;

– The International Mobile Equipment Identity (IMEI) ; or

– The International Mobile Equipment Identity together with the Software Version number (IMEISV).

8

7

6

5

4

3

2

1

Octet 1

IEI

Octet 2

Length Indicator

Octet 3

Octet n

The rest of the information element is coded as the value part of the mobile identity IE defined in 3GPP TS 04.08 (not including 3GPP TS 04.08 IEI and 3GPP TS 04.08 length indicator).

Figure 18.4.16/3GPP TS 09.18: Mobile identity IE

18.4.17 Mobile station classmark 1

The purpose of the Mobile Station Classmark 1 information element is to provide the network with information concerning aspects of high priority of the mobile station equipment.

8

7

6

5

4

3

2

1

Octet 1

IEI

Octet 2

Length indicator

Octet 3

The rest of the information element is coded as the value part of the mobile station classmark 1 IE defined in 3GPP TS 04.08 (not including 3GPP TS 04.08 IEI)

Figure 18.4.17/3GPP TS 09.18: Mobile station classmark 1 IE

18.4.18 Mobile station state

The Mobile station state IE is a TLV IE that indicates to the VLR the GMM and GSM states of the MS in the SGSN. The coding of the V field is as follows.

8

7

6

5

4

3

2

1

Octet 1

IEI

Octet 2

Length indicator

Octet 3

Mobile station state value

Figure 18.4.18/3GPP TS 09.18: Mobile station state IE

Table 18.4.18/3GPP TS 09.18: Mobile station state IE value part

Mobile station state value (octet 3)

Bits

8 7 6 5 4 3 2 1

0 0 0 0 0 0 0 0 IDLE

0 0 0 0 0 0 0 1 STANDBY, 0 PDP contexts active

0 0 0 0 0 0 1 0 STANDBY, 1 or more PDP contexts active

0 0 0 0 0 0 1 1 SUSPENDED, 0 PDP contexts active

0 0 0 0 0 1 0 0 SUSPENDED, 1 or more PDP contexts active

0 0 0 0 0 1 0 1 READY, 0 PDP contexts active

0 0 0 0 0 1 1 0 READY, 1 or more PDP contexts active

0 0 0 0 0 1 1 1 IMSI unknown

0 0 0 0 1 0 0 0 Information requested not supported

0 0 0 0 1 0 0 1 Shall not be sent in this version of the protocol.

to If received, shall be treated as ‘00001000’.

1 1 1 1 1 1 1 1

18.4.19 PTMSI

The PTMSI consists of 4 octets. It can be coded using a full hexadecimal representation (see 3GPP TS 03.03).

8

7

6

5

4

3

2

1

octet 1

IEI

octet 2

length indicator

octet 3

PTMSI octet 1

octet 4

PTMSI octet 2

octet 5

PTMSI octet 3

octet 6

PTMSI octet 4

Figure 18.4.19/3GPP TS 09.18: PTMSI IE

18.4.20 Reject cause

The purpose of the Reject Cause information element is to indicate the reason why a request from the mobile station is rejected by the network.

8

7

6

5

4

3

2

1

Octet 1

IEI

Octet 2

Length Indicator

Octet 3

The rest of the information element is coded as the value part of the reject cause IE defined in 3GPP TS 04.08, not including 3GPP TS 04.08 IEI.

Figure 18.4.20/3GPP TS 09.18: Reject cause IE

18.4.21 SGSN number

The SGSN number is coded as a sequence of TBCD digits (as specified in 3GPP TS 09.02), compressed two into each octet. The Number is in international E.164 format as indicated by Octet 3 which coding is specified in 3GPP TS 09.02. This is a variable length information element, and includes a length indicator. The value part of the SGSN number information element (not including IEI, Length indicator and Octet 3) shall not exceed 15 digits.

8

7

6

5

4

3

2

1

Octet 1

IEI

Octet 2

Length indicator

Octet 3

1

0

0

1

0

0

0

1

Octet 4

digit 2

digit 1

Octet n

digit i+1

digit i

Figure 18.4.21/3GPP TS 09.18: SGSN number IE

18.4.22 TMSI

The TMSI consists of 4 octets. It can be coded using a full hexadecimal representation (see 3GPP TS 03.03).

8

7

6

5

4

3

2

1

octet 1

IEI

octet 2

length indicator

octet 3

TMSI octet 1

octet 4

TMSI octet 2

octet 5

TMSI octet 3

octet 6

TMSI octet 4

Figure 18.4.22/3GPP TS 09.18: TMSI IE

18.4.23 TMSI status

The purpose of the TMSI status information element is to indicate to the VLR whether a valid TMSI is available in the MS.

8

7

6

5

4

3

2

1

Octet 1

IEI

Octet 2

Length indicator

Octet 3

Spare

TMSI
flag

Figure 18.4.23/3GPP TS 09.18: TMSI status IE

Table 18.4.23/3GPP TS 09.18: TMSI status IE value part

TMSI flag (octet 3)

Bit

1

0 no valid TMSI available

1 valid TMSI available

Bits 2-8 in octet 3 are spare and shall be coded all equal to 0.

18.4.24 VLR number

The VLR number is coded as a sequence of TBCD digits (as specified in 3GPP TS 09.02), compressed two into each octet. The Number is in international E.164 format as indicated by Octet 3 which coding is specified in 3GPP TS 09.02. This is a variable length information element, and includes a length indicator. The value part of the VLR number information element (not including IEI, length indicator and Octet 3), shall not exceed 15 digits.

Table 18.4.24/3GPP TS 09.18: VLR number IE

8

7

6

5

4

3

2

1

Octet 1

IEI

Octet 2

Length indicator

Octet 3

1

0

0

1

0

0

0

1

Octet 4

digit 2

digit 1

Octet n

digit i+1

digit i