| 摘要 |
PURPOSE:To identify from whom a telephone call comes before reply by inserting a caller number to a pause time of a call signal sent to a called telephone set and sending the signal. CONSTITUTION:An exchange program of an exchange connects a called telephone set 1 to an RGT 3 via a network 2 with an well-known method and after a pre-loop test for the called subscriber is conducted, a pattern relay S is actuated via a relay drive controller 4 and then an inter-relay INT is intermitted. An exchange program takes a prescribed guard timing T required for the preparation of a PB signal reception circuit, converts the caller telephone number into a PB signal and operates sequentially one of L1-L4 group and H1-H3 group corresponding to the said frequency. Thus, the PB signal generated by a PBOSC 32 is sent to a PBOST 33 to the telephone set 1, on which caller subscriber number information is displayed. |
