| 摘要 |
PROBLEM TO BE SOLVED: To provide a telephone system connected to an ISDN line by using only a digital signal that can inform a busy digital cordless slave unit about the arrival of an incoming call from an external line in spite of being unable to transmit a notice signal to the slave unit during an extension call between digital cordless slave units. SOLUTION: In the case of the arrival of an incoming call from a channel during an extension speech between the digital cordless slave units, the telephone system realizes a pseudo catch-phone function for the digital cordless slave units by interrupting the extension speech between the digital cordless slave units and informing the digital cordless slave units about the arrival of the incoming call coming from the channel.
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