Telephone communication system

摘要

A telephone communication system in which a call-originating side and a call-incoming side communicate by telephone via a communication network capable of wideband communication and narrowband communication. When an apparatus exclusively used for narrowband communication, an apparatus capable of wideband communication and narrowband communication, and an apparatus exclusively used for wideband communication exist mixedly in between one end and another end, at least one of phone-call path parts between adjacent ones of the apparatuses is set to be different in transmission capability on a per phone-call path part basis, by sending and receiving information about transmission capabilities of the apparatuses in between the one end and the another end.