| 摘要 |
PURPOSE:To attain multi-party communication by providing a means or the like receiving a multi-frequency code dial signal for plural number of times so as to call plural optional called parties in plural 4-wire telephone sets selectively connected to a 4-wire multi-party line. CONSTITUTION:Four-wire telephone sets TEL10-40 each consist of a transmission circuit XMT2, a reception circuit RCV3 and a control circuit CTL4 or the like and the RCV3 can receive a multi-frequency code MFC dial signal for plural number of times. If a communication request takes place from the TEL10 to the TEL40 further during the communication in the TEL10 and the TEL20, the TEL10 sends an MFC signal corresponding to the TEL40 to a transmission line LA5. The MFC signal is received by the RCV 3 via the reception circuit LB5 at the side of the TEL40, and the circuit CTL4 discriminates that itself is a called party, a bell rings and the TELs 10, 20, 40 are in the state of 3-party communication by the called party reply by the TFL40. Thus, plural optional called parties among TELs in multidrop connection to the 4-wire line 5 are subject to selective call and multi-party communication is attained among the TELs.
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