Abstract: A mobile telephone unit which combines operation of a respective portable mobile telephone and a communication unit. The mobile telephone unit includes at least one portable telephone, a communication unit and a buffer unit. The communication unit includes an external connection terminal, a radio transmitter/receiver, a baseband processor, a communication controller and a handset. The buffer unit mounts at least one portable mobile telephone.

Abstract: In a packet transmission system in which a plurality of kinds of telephone signals are packetized and transmitted, when a voice signal call is originated, a real channel is established for the voice signal call prior to a signal call other than a voice signal call, so that a transmission channel is occupied in each frame. When the voice signal call is over, the transmission channel allocated to the voice signal call, is changed to a condition in which another call can be allocated thereto. The system is useful for effective utilization of a packet communication network, without impairing the transmission quality requirement for a voice signal call.