PHONE CALL CONTROL SYSTEM HAVING PROVISION FOR POWER SAVING, ISDN CHANNEL USE TERMINAL ADAPTOR USING THE SAME AND TELEPHONE SET

摘要

PROBLEM TO BE SOLVED: To save consumption of a power failure backup battery by making a buzzer circuit with small power consumption available in the vicinity of a telephone set in the case of applying an incoming call notice to the telephone set contained in a terminal adaptor.;SOLUTION: Upon the receipt of an incoming call by a terminal adaptor side telephone set control circuit 10, a -48 V feeding ring signal transmission circuit 11 supplies a signal resulting from superimposing a ring signal onto a -48 V power supply to a telephone set 30 usually and a -24 V power supply circuit supplies a -24 V power supply to the telephone set 30 on the occurrence of a power failure. A buzzer circuit 20 that rings when detecting application of a voltage of -30 V--10 V is connected in the vicinity of the telephone set connected to a connection line 40. When the telephone set replies the call and reaches a speech state, a terminal voltage of the telephone set drops to a voltage of ≤-10 V and the buzzer circuit stops ringing. Since a ring signal with 75 V rms requiring large power consumption is not used, the current consumption of a battery can be reduced.;COPYRIGHT: (C)2001,JPO