| 摘要 |
PROBLEM TO BE SOLVED: To reduce electrical communication cost, that is related to leaving a voice message of a long distance call or a toll call on a different time base by providing a means which transmits a calling subscriber message to be reproduced later from a calling subscriber communication device to a called subscriber communication device via a 2nd network. SOLUTION: A communication network 100 includes a calling subscriber communication device 102 and a called subscriber communication device 104, and both the devices 102 and 104 perform mutual communication via a central station 106 of a public switching network or a communication link 108 of a packet switching network. When a calling subscriber leaves a message for a called subscriber who cannot answer the call, the communication is automatically switched to a network of higher cost and then the calling subscriber transmits a message, that is to be reproduced later by the called subscriber via a packet network of lower cost. As a result, the duration is reduced for a tall call on a time base, that is transmitted via a public switching network of higher cost, and accordingly the total cost of communication is reduced.
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