Method of requesting security and release of communication band

A communication band securing method for use in an IP telephone network including a plurality of router apparatuses each of which can secure a band width used in communication between terminals and can release a used band width, an IP network constituted by said plurality of router apparatuses, one or more telephone networks having telephone terminals connected thereto, a gate keeper apparatus connected to said IP network, one or more IP telephone gateway apparatuses through which said IP network and said telephone networks are connected to each other, and one or more IP telephone terminals connected to said IP network,

• wherein when communication is carried out between said IP telephone gateway apparatuses, between said IP telephone terminals, or between the associated one of said IP telephone terminals and the associated one of said IP telephone gateway apparatuses, said gate keeper apparatus obtains the call terminating side IP telephone gateway apparatus or the call terminating side IP telephone terminal corresponding to a call terminating side telephone number accompanying a communication request received from the call originating side IP telephone gateway apparatus or the call originating side IP telephone terminal, and when a communication band width secured on a communication path between the call originating IP telephone gateway apparatus and the call terminating side IP telephone gateway apparatus or between said IP telephone terminals is narrower than the total communication band width after establishment of the connection based on the communication request, said gate keeper apparatus requests the associated one(s) of said router apparatuses disposed on the communication path to secure additionally a band in the previously specified additional band width wider than the communication band width required for the communication to inform the call originating side IP telephone gateway apparatus or the call originating side IP telephone terminal, and the call terminating side IP telephone gateway apparatus or the call terminating side IP telephone terminal of a result of the request.