Introduction

The purpose of this Recommendation is to define the general interworking requirements between the telephone network and the INMARSAT Standard A system.

In order to support automatic working between subscribers in the public telephone service and telephone subscribers to the maritime mobile-satellite service, it is necessary that the interface between the terrestrial telephone network and the maritime satellite system be defined.

It should be possible to interface the maritime-mobile satellite system with any signalling system standardized by the CCITT for automatic working. In order to facilitate the preparation of the interworking equipment, and also aiming at the international standardization of the service, this Recommendation lists several basic interworking requirements common to all signalling systems.

More specific interworking requirements applicable to System No. 5 are given in Recommendation Q.1103 and System R2 are given in Recommendation Q.1102.

A brief description of the INMARSAT Standard A system is given in Annex A. SDL descriptions of incoming and outgoing signalling procedures for the INMARSAT system are given in Annexes B and C respectively.

Interworking between the telephone network/ISDN and other INMARSAT systems is given in separate Q-Series Recommendations.