| 摘要 |
In a key telephone system in which a plurality of data terminals 371 . . . 37n such as personal computers are connected to a key service unit 1 connected to a plurality of telephone lines 251 . . . 25m, a modem 43 is pooled so as to be usable in common for the plural data terminals 371 . . . 37n. In response to a called party number signal from the Telephone line (e.g. 251), the key service unit 1 selects a single data terminal among the data terminals 371 . . . 37n now being in standby status, and closes a communication channel between the selected data terminal (e g 371) and the modem 43, so that a status equivalent to that where the selected data terminal 371 and the modem 43 are directly connected to each other can be established. Thereafter, the key service unit 1 indicates a called party number signal reception to the modem 43, and the modem 43 transmits a call to the selected data terminal 371. When the selected data terminal 371 responds to the call from this modem 43, the key service unit 1 closes a communication channel between the modem 43 and the telephone line 251, so that a communication link between the selected data terminal 371 and the telephone line 251 can be established via the modem 43. During the process until this communication link can be established, since the selected data terminal 371 and the modem 43 are in the status equivalent to direct coupling, the key service unit 1 is not concerned in the communications between the selected data terminal 371 and thus modem 43, thus reducing the operational load applied to the key service unit 1.
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