| 摘要 |
PROBLEM TO BE SOLVED: To allow only a master set or a slave set of the highest speaking frequency corresponding to the telephone number of a caller, to ring when a call incomes next after registering the speaking frequencies of the master set or the slave set corresponding to the telephone numbers of the caller. SOLUTION: The master set 1 and the plural slave sets 2, 3 and 4 are connected to a single telephone line. A modem 8 receives the telephone number of the caller when the call incomes. A CPU 5 judges whether the number of the caller is registered. When a slave set interface 9 judges that the number is registered, it allows a telephone set of the highest speaking frequency to ring in accordance with the telephone number of the caller. When the speaking is finished, a main memory 6 stores the speaking time in a speaking frequency table (S25) and stores the identification number of the telephone set of the highest speaking frequency in a ringing telephone set table (S27).
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