| 摘要 |
PURPOSE:To enable a system to stand-by automatically at the operation of an exchange when an originating subscriber encounters circuit congestion and to make an automatic connection when one circuit becomes free. CONSTITUTION:When a subscriber hooks off a handset and dials a special trunk outgoing number and a junction line encounters bus congestion, central controller CC connects subscriber SUB to talkie sound transmitting trunk TKYT and stores memory unit M with the route number of junction line determined by an extension subscriber's number and the dial number. Then, SUB is informed by a talkie tone that a stand-by state is set. Next, CC exercises a periodic superivision over the free/blocking state of the junction line of the route number stored in M by a program and, when a free junction line is found, connects the trunk PVT to SUB to delete stand-by information stored in M, thereby resetting the stand-by state. |
