To assign automatically and quickly end-to-end communication channels between a communication equipment group and a node group by forming a group of optional communication transmission channels between both groups in a network system consisting of a communication equipment group and a node group interconnected via various communication networks.

On the occurrence of the arrival of a call from communication devices 10-60, a communication channel information of the network and terminal transmission channels 190-210 required for selection of a group of communication channels registered in advance is automatically selected and extracted from a database, based on information sent by the communication devices 10-60. A controller 120 executes reservation of an end-to-end communication transmission channel for the communication device group via the terminal transmission channel switch-over and network.