TELEPHONE COMMUNICATION SYSTEM

摘要

There is provided a telephone communication system capable of maintaining a high communication quality even when a device intending a wide band communication and a device intending a narrow band communication are mixed on the communication path. In the telephone communication system, a caller side and called side telephone-communicate via a communication network capable of performing wide band communication and narrow band communication. When a device dedicated to narrow band communication and a device capable of wide band communication and narrow band communication or a device dedicated to wide band communication are mixed between end-to-end, by transmitting/receiving transmission ability between devices of end-to-end, a different transmission ability is set to a part of communication path based on a unit of the communication path portion between adjacent devices.