| 摘要 |
PURPOSE:To prevent an erroneous connection of a line by detecting a dial pulse as early-stage pulse and performing abnormal call processing when the dial pulse arrive from an opposite station before specific timing. CONSTITUTION:A relay J is energized by the incoming call from the opposite station through a trunk line TRL to make its make contact j1, operating a relay K. If a dial pulse signal arrives from the opposite station before this relay K operates, the relay J operates to make its break contact j2 again and the relay R is grounded through a make contact k7, break contact j2, and break contact ck0 to operate. Then, the relay R holds the operation by a self-holding contact r1 until the loop actuation from the opposite station is released. Once the relay R operates, the break contacts are broken to cut off the loop actuation to an exchange and a connection with a register is aborted. Further, a make contact r3 is made to send a busy tone. |
