| 摘要 |
PURPOSE:To make it possible to take a circuit without putting back the handset tempolarily even when a leased-line route is busy, by equipping a switchboard with a detecting method for hooking or constant-period holding. CONSTITUTION:Switchboard EXC is provided with memory unit MEM and hooking detecting method HS. To MEM, the special number of a leased-line route and the number of a party main-wire subscriber are assigned. If leased-line trunk PBWT is in use, subscriber SUB makes hooking operation by hearing a busy tone. As a result, hooking detection method HS detects this and the switchboard acquires office trunk COT. Once COT is acquired, an main-wire subscriber's number is extracted from leased-line route numbers stored in MEM and sent out from the outgoing sender. Further, it is possible to make a circuit after a fixed time from the arrival of a busy tone. |
