6 Interworking classification

09.043GPPInterworking between the Public Land Mobile Network (PLMN) and the Circuit Switched Public Data Network (CSPDN)TS

6.1 Service interworking

No service interworking has been identified as a requirement of the GSM system.

6.2 Network interworking

Network interworking is required whenever a PLMN and a non-PLMN together are involved to provide an end to end connection and may be required in instances of PLMN to PLMN connections.

The concept of Bearer Services was developed for the ISDN and has been extended to GSM in accordance with GSM 02.02. A bearer service is defined as:

A type of telecommunication service that provides the capability for the transmission of signals between user-network interfaces.

Access at

mobile station

Connection Type

Data transmission

service in CSPDN

Bearer Service

in ISDN

Data cct duplex

synchronous 2,4 kbit/s

Circuit mode unstructured

(8 kbit/s) with unrestricted

digital capability

circuit switched

user class 4

Data cct duplex

synchronous 4,8 kbit/s

Circuit mode unstructured

(8 kbit/s) with unrestricted

digital capability

circuit switched

user class 5

cct mode structured

64kbit/s unrestricted

Data cct duplex

synchronous 9,6 kbit/s

Circuit mode unstructured

(16 kbit/s) with unrestricted

digital capability

circuit switched

user class 6

The network interworking is described in clause 7.

6.3 Signalling interworking

6.3.1 Connection CSPDN

PLMN is connected to CSPDN using an interworking function according to CCITT X.300.

The interface between IWF and CSPDN is in accordance to CCITT X.71 (Direct interworking). If PLMN is connected to CSPDN via ISDN the interface to ISDN shall be according to GSM 09.07 and the information rate adapted according to CCITT X.30.

6.3.2 Multiplexing schemes, CCITT X.51

The multiplexing schemes for the X.71 connections shall be in accordance with CCITT X.51. Housekeeping bits shall be allocated in the same way as for DSE to DSE in CSPDN.

6.3.3 Allocation of channels, X.54

The allocation of channels on the X.71 connection shall be according to CCITT recommendation X.54.

6.4 Numbering

Numbering shall be in line with GSM 03.70.

6.5 Supplementary service interworking

Supplementary service interworking between GSM PLMN and CSPDN is described in GSM 02.04, GSM 02.8x and 02.9x-series, GSM 03.11, GSM 03.8x and 03.9x-series, if applicable.