Details definitions, minimum physical layer performance requirements, environment and testing requirements of mobile terminals for accessing the mobilesat(sup)TM(/sup) satellite communications system owned and operated by OPTUS Communications. The specifications cover signalling and telephony requirements to ensure access to the system, attainment of intended service quality, interworking with the network management station, base stations and gateways, and also to ensure that the terminals will not in any circumstance endanger system integrity. Mechanical specifications for terminals, the numbering scheme, or possible user interfaces for enhancement facilities are not covered. This Standard is intended for use by terminal equipment designers, manufacturers, suppliers and maintenance personnel, to ensure correct operation of mobile terminals and their compatibility with the mobilesat(sup)TM(/sup) communications system.