The GSM network may be complemented with another network to reach to the service provider(commonly called PSTN/ISDN). In order to allow access to the GSM network, the user terminal shall be provided with a GSM Interaction Module(IM) referred to as a Mobile Station(MS).
The Interface between the GSM network and MS shall be compliant with the standard requirements on general on Terminal Adaptation Function(TAF) for Mobile Station(MS) as reported in ETS 300 582[12].
