Abstract: A communications operating system is provided herein. The communications operating system having a common communication system comprising a radio frequency transceiving means for transmitting and receiving radio frequency signals and a system list means for storing a list of communication systems available. The system also includes a feature list means for storing a list of feature programs, where the feature programs comprise at least one of an enabling program to enable resident functions, a high-level design specification, and an executable feature specification.

Abstract: A method and apparatus enables selection a communication system when a user of a mobile unit is away from a home system to which it is registered. According to one novel aspect, the visited communication system broadcasts (402) a list of standardized type services including tariff information, which is used by the mobile unit to select a system. According to another novel aspect, the mobile initiates an outgoing call of a non-standardised type service by accessing (502) a candidate system and informing it of the location of the home network and desired service identifier. The candidate system obtains (504) the service information on this service from the home network, and then provides (546) a quotation for a required service. Also, a communication system according to the present invention minimises incoming call costs to the user wherein the home system polls (606) the communication systems within range of the mobile unit to select the best system to provide service.

Abstract: In a TDM communication system (100), full duplex communication is provided for two communication units(104) and (105) which communicated communication messages through a repeater (102). Communication messages transmitted from the communication units (104) and (105) are combined in the repeater (102) to produce a combined communication message. The repeater (102) transmits the combined communication message to the communication units (104) and (105). The communication units (104) and (105) remove from the combined communication message the communication the previously transmitted communication message so as to recover the communication message from the other communication unit.

Abstract: A time division multiplexed system is disclosed in which communication messages among a wide area site and a plurality of substantially scattered local sites are communicated on a radio frequency channel which is divided into a plurality of time slots, wherein at least one of the time slots is further divided into a plurality of subslots. Communication units operating in the wide area site communicate communication messages during the time slots, and the communication units operating in the local sites communicate communication messages during the subslots which are assigned to each of the local sites.