| 摘要 |
PURPOSE:To effectively perform a telephone exchange by regulating optionally an extension trap number of one digit after a line wire connection state is generated preferentially corresponding to an off-hook, and performing a switching to an extension connection state corresponding to a dial outgoing. CONSTITUTION:When a call by the off-hook is performed at either of telephone sets 4, a loop detection circuit 13 detects it, and when it is a telephone set 4a or 3b, relays LA and LB are recovered, and when it is either of telephone sets 4c-4n, relays LC-LN are operated, and a connection to a telephone circuit 2 is performed. Next, when the dial outgoing is performed, the circuit detects it, and when it is a series of line wire outgoing numbers, a control circuit 15 performs a line wire connection, but, when it is an extension number of one digit, the repeat operation of the relays LA and LB or the recovery of the relays LC-LN is performed, and the tone ringer of a caller telephone set is rung and an incoming is informed.
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