To obtain a packet telephone system which is provided with service quality to be approved and has no relation to a network load by deforming a received communication signals so as to keep the service quality of a data communication network to ≤ a threshold value level regardless of the network load.

A network terminating unit 200 is connected to the data communication network 108 to be a basis and a packet telephone network terminating device 104 with a communication link 106 so as to form a part of one end of the packet telephone system. The network terminating unit 200 is constituted by processing the communication signal concerning the data communication network 108 and keeping the service quality of the network 108 to ≤ the threshold value level regardless of the network load. Therefore, a network operator or a user can optionally or intentionally set the threshold value level of service quality in the packet telephone system.