Patent GB-1210150-A (GB)
Title: Mobile radiotelephone communication system
IPC: H04W68/00
Filed: 1968-12-19
Abstract: 1,210,150. Automatic exchange systems. INTERNATIONAL STANDARD ELECTRIC CORP. 19 Dec., 1968 [21 Dec., 1967], No. 60325/68. Heading H4K. In a radio-telephone communication system, subscribers connected to a wired network can communicate with subscribers having mobile radio telephone sets and can alert subscribers having mobile call warner sets via a radiotelephone base station which has means to store a plurality of call warner set numbers for transmission when a radio speech channel becomes free and means to alternately offer a speech channel for call warner and radio-telephone use. The system may be generally similar to those described in Specifications 1,190,865, 1,200,403 and 1,210,169. In one form in which the radio system covers an extensive area there are a plurality of base stations employing different speech channel frequencies and a common frequency service channel, all free mobiles housing to the common channel. Other forms not employing a service channel are suggested. In one form a free channel is marked with a tone and all radio-telephones standby in this channel, the channel being taken into use for a call in either direction. In another form the radiotelephones home on a channel marked for an incoming call and move to another marked channel for an originating call. A system employing radio operators and in which selection signals are broadcast over all free channels is also sugested. In any form dialling signals arriving from wired substation or from a radio-telephone mobile are entered in a register. If the number is that of a wired substation the call is established in known manner but if the register recognizes the call as a paging signal i.e. the number of a call warner it is forwarded and entered in an associative store at a base station. The write-in device of the store or the register incorporate a translator which determines the channel to be used and the number to be transmitted from the dialled designation, the call warner sets being distributed evenly over the speech channels and being each permanently associated with a single channel. Each channel is offered alternatively for call warner use and for full radio telephone use. When a channel is offered for call warner use the store is searched for call warner calls to be sent out over that channel and up to a predetermined number of such call warner numbers are transmitted over the channel before its again offered for radio-telephone use. The order in which free channels offered for call warner use are selected may depend on the chronological order of received call warner calls, on the quantities stored for each channel or may be chosen cyclically. When a channel is offered for radio-telephone use the call may be automatically interrupted after three minutes. If a call to a radio-telephone mobile arrives while no channel is free but a channel is in use for call warner service, the marker waits until this channel becomes free and only returns busy tone if the channel is not allotted for a terminating call, i.e. an incoming call can camp on a busy channel being used for call warner service.