PURPOSE: To prepare an electronic switchboard that can eliminate the disconnection of a call caused by the abnormality of call information in a control system and that can maintain the continuity o talking service by using switch connection information stored in the speech path equipment to save the talking service.
CONSTITUTION: By information in the holding memory of speech path equipment, the storage positions at busy sending and receiving sides on speech path switch and the speech path switch that connects these positions are discriminated, and these positions are set into a saving service state. The call transition signal that is sent from a subscriber HN is received and detected to discriminate a connecting service state, and if this connecting service state is other than the saving service state, various ordinary services are executed. Further, when the connecting service state is the saving service state, if a received signal is a response signal, the response processing is executed, or otherwise, call disconnection processing is executed. With this, even in case abnormality occurs in the control system equipment, call saving can be realized, and the change of saving processing accompanied by service addition can be reduced.
INOUE TAKATSUGU
SATO TAKAAKI
NIPPON TELEGRAPH & TELEPHONE