| 摘要 |
PURPOSE:To improve services to a subscriber by removing the ineffective holding of a circuit, by allowing a terminal unit equipped to the text circuit to detect automatically that a party subscriber has been released first. CONSTITUTION:When the party is released first after a connection to a terminal unit via a telephone network, releases of actuation display relay L and actuation cutting relay C of the subscriber's circuit both start and while slow relay C is operating, busy tone BT is sent out to the terminal unit. In the terminal unit, the busy tone allows busy-tone detection relay BTC to operate automatically and, in consequence, the loop circuit at the terminal unit side is disconnected at contact (btc<0>), thereby attaining the disconnection from the telephone network. |
