JPS5671362A - Recallout system of trunk line relay board - Google Patents

Abstract

PURPOSE:To avoid the necessity of waiting with a hand set in hand for extension subscribers until the relay board operator responds, by providing a recall detection circuit detecting the operating signal of a telephone set with the trunk line trunk, in recalling the trunk line relay board from an extension telephone set during connection. CONSTITUTION:With the dial pulse or hook switch operation determined to recall the trunk line relay board operator from an extension TEL, the dial pulse relaying and communication monitor relay A is operated. Further, with the operation of the relay A, the recall detection circuit RDET is operated, the telephone set is hooked on, and when a recall signal is detected, the recall detection relay RC is activated. Recall display is made to the lamp L of the position device POS with this relay RC. Next, after the recall display of the operator of the trunk line relay board, when the trunk line COTRK is caught with the board operation, the extension TEL is called from the device POS. Thus, the extension subscribers need not to carry a handset in hand until the operator responds, in recalling the relay board operator.