METHOD OF TRANSMITTING TERMINATING CALL SIGNALS WITHIN A RESTRICTED DURATION AND A BASE STATION AND A PORTABLE UNIT FOR USE IN THE SAME

In a method of calling a portable unit from a base station through a radio control channel, a succession of terminating call signals is sent through the control channel from the base station to the portable unit for a first or restricted duration (T1) selected in consideration of a battery saving period of a battery saving operation carried out in the portable unit. Within the battery saving period, the portable unit is put into transient active and inactive states during a first time interval and a second time interval, respectively. Selection is made so that the first duration be longer than the second time interval to receive at least one of the terminating call signals within the first duration in the portable unit. The base station monitors an acknowledgement signal for a second duration (T2) after lapse of the first duration and interrupts the control channel when the acknowledgement signal is not received within the first and the second durations. In the portable unit, the battery saving operation is released when presence of the terminating call signals is detected by a squelch circuit.