The power failure corresponding manner of the key telephone system and the ISDN circuit by the power failure corresponding

摘要

PROBLEM TO BE SOLVED: To answer an incoming call by making a residual channel receive the incoming call without causing a failure state when one B channel is used for speech during receiving the incoming call by a representative master number.;SOLUTION: In the case of making an ISDN line representatively select an incoming call, although a channel control circuit 22A can make a residual B channel busy and notify an ISDN of network determination user busy of the line while lines 1 and 2 use a B channel 1 respectively, the channel control circuit 22A calls a user by ringing or the like from an incoming call circuit 23 when the residual B channel 2 receives the incoming call, and responds to the ringing call by the B2 channel and makes the busy B1 channel be held when receiving the operation of user's channel switching manual switch 24A. In the next user's operation of the channel switching manual switch 24A, speech and holding of the B1 and B2 channels are alternately repeated.;COPYRIGHT: (C)2008,JPO&INPIT