| 摘要 |
PURPOSE: To provide a call maintenance system for a portable telephone set to make a slave unit substitute for a master unit when the master unit is kept in an unreachable range of radio waves and also to secure the automatic answering telephone function of the slave unit. CONSTITUTION: The information (S1+D1) and (S2+D2) obtained by adding the priority to the position information are registered in a center memory 3 by a master unit 1 and a slave unit 2. When a call is produced in a telephone network 6, a calling station 4 first calls the unit 1 based on the information (S1+D1) and (S2+D2) stored in the memory 3. If the unit 1 is kept in an unreachable range of radio waves and therefore no answer is received from the unit 1, the unit 2 is called and the calling contents are recorded by the automatic answering telephone function of the unit 2.
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