| 摘要 |
PURPOSE:To abbreviate the holding time of a common control unit by opening a call to the pick-up telephone set in a call pick-up trank. CONSTITUTION:When the special number of call pick-up service requirement and the number of discriber TELA to be picked-up are dialled in telephone set TELB, bridge cut off of telephone set TELA in incoming call occurs through the call pick- up trank. In this case, call signal receiving circuit RTA with high impedance in the call pick-up trank confirms that the call to be picked-up is in calling, so that a DC loop is formed in TELB side and ring trip circuit RT is formed in incoming call. Then, the channel between TELB and TELA is opened in the call pick-up trank. |
