PURPOSE: To discriminate telephone sets by a dial signal to make disconnection of needless trunks possible, by connecting originating register trunks for DP telephone set and PB telephone set in parallel and by operating both trunks simultaneously by originating of one telephone set.
CONSTITUTION: DP telephone set 1 and PB telephone set 2 are connected to the branch connection line. For dial receiving from subscriber 3, subscriber 3 is connected to originating register trunks 8 and 9. Since the telephone set which originates is not discriminated when originating starts, line 4 is connected to both trunks temporarily by primary switch 16 in line link network in control circuit 15, and closing of the channel is confirmed, and simultaneously, dial tone is transmitted. In case of on-hook of PB 2, the SP signal of detector 11 is output by the multifrequency signal dependent upon dialing, and photocoupler 20 and the SP relay are operated to confirm oscillation from PB. In case of on-hook of DP 1, relays 17 and 18 are released, and the A relay is operated intermittently, thereby confirming DP.
FUJITA TAKAO
HATANAKA TOSHIKI
| JP46026093U | ||||
| JPS52127105A | 1977-10-25 |