| 摘要 |
PURPOSE:To always allow the detection of an answer and to eliminate a signal device on another stage for a private exchange, by detecting a call with a single line of a paired telephone calling circuits of a relay device and then connecting the other line directly to a single line of a paired exchange telephone circuits. CONSTITUTION:When the calling starts, a battery is supplied to a line B from an intra-office trunk IOT to actuate a relay R. While the call signal given from a signal device SIG is transmitted from the trunk IOT. This is eqivalent to the fact that the battery for detection of answer shifts to a trunk TELT for a countermeasure for line unbalancing from the trunl IOT. When an extension telephone TEL gives an answer, the answer is directly detected by the relay RT of the trunk IOT. Thus the relay R is recovered. As a result, a relay J works with an answer loop of the telephone TEL. Then a relay B works. The answer loop is sent back to the trunk IOT via the contacts J<1> and b<1>. |
