Introduction Purpose The purpose of this Recommendation is to standardize: a) the selection procedures for subscribers in the public switched telephone network or ISDN calling a ship earth station in the INMARSAT systems; b) the procedures for calling a subscriber@ an operator or a special service termination in the public switched telephone network or ISDN from a ship earth station. This Recommendation applies to INMARSAT Standard-A@ B and C systems. Selection procedures for the INMARSAT Aeronautical system is for further study.