Abstract: An audio gateway is provided for receiving an internet relay request and a number called in a call from a telephone via the internet. An audio data gateway is selected using the number called, and relay operations are performed with the selected destination audio data gateway. The relay audio data is multiplexed for streams based on multiple relay requests having the same relay destination so that the relay audio data in these streams are multiplexed into a single relay stream.

Abstract: By adopting a method of requesting a band for each plurality of calls, or a method of requesting a band independently of origination or termination of a call, a method of reducing the frequency of origination of a call is provided. A first aspect may provide that a gate keeper requests security and release of a band not every call, but collectively for a plurality of calls, and the security and the release of a band are requested at frequency less than that of origination or termination of calls. A second aspect may provide that an estimated value of a time series change in necessary band is previously set in a gate keeper, and security and release of a band required for communication are requested depending on a time, but independently of origination and termination of a call.

Abstract: A gateway (GW) for relaying a communication between a public telephone network and a routing server for managing use status of the GW and a network are provided on the internet. When a connection request is received, the GW issues a request to retrieve a route in which the costs are minimum and a necessary bandwidth can be reserved. The routing server retrieves the route of the minimum costs using the bandwidth reservation status of the internet and the partner's telephone number and notifies the request issued GW of the address of the partner GW. The costs at that time point may be notified to the user and the user selects whether the communication is performed or not. By managing the current connection information established by each GW, if a necessary bandwidth cannot be reserved, an audio compression ratio may be changed.