TELEPHONE SYSTEM FOR CONNECTING PUBLIC NETWORK AND INTERNET PROTOCOL NETWORK

摘要

PROBLEM TO BE SOLVED: To provide a telephone system in which a call is prevented from being unestablished even when a media stream is established in the case of originating the call from an existent telephone set to an IP telephone.

SOLUTION: In the telephone system for connecting the public network and the IP network, an exchange is provided with: an inquiry part for judging whether an incoming side corresponding to an incoming dial number sent from the telephone set is the IP telephone or not and for transmitting an inquiry message on whether or not a required audio band is to be guaranteed to a corresponding call agent when the incoming side is the IP telephone; and a connection request part for transmitting a connection request message to the call agent when a response message to the inquiry message is a positive response representing that the required band can be guaranteed. The call agent is provided with: a band decision part for deciding whether or not a corresponding media gateway can guarantee the required voice band on a communication path of the IP telephone side based upon the inquiry message; and a response part for transmitting a response message representing whether the required band can be guaranteed or not to the exchange.

COPYRIGHT: (C)2004,JPO