Abstract: This invention appropriately regulates or controls a simultaneous communication between different communication methods. When a request of a voice communication is made with respect to a communication terminal 4 which is currently busy with a packet communication from a communication terminal 1, a voice incoming signal is generated at a voice line controller 20. Then, a communication terminal state request is output from the voice line controller 20. This is transmitted to a data base 30 through a data exchange device 21. Then, the data base 30 reads voice line memory AB, packet line memory PB and transmits the same as a communication terminal state response to the voice line controller 20 through the data exchange device 21. As a consequence, the voice line controller 20 can know the communication state of the communication terminal 4 and determines whether or not the voice communication circuit should be connected based on it.

Abstract: In order to provide a packet transfer scheme in which various data can easily be used commonly with other communication methods and a packet can be transferred at a high speed, a mobile communication system comprises a database (20) for storing an identification number of a mobile terminal (40) and location information indicating a zone in which the mobile terminal is currently located, a packet switch (10), and another packet switch (30) capable of communication when the mobile terminal (40) is located in a zone under the packet switch (30). The packet switch (10) inquires of the database (20) about the location information of the mobile terminal (40) when the packet switch (10) receives a packet addressed to the mobile terminal (40). When the mobile terminal (40) is located in the zone under the packet switch (30), the packet is transferred to the mobile terminal (40) through the packet switch (30).