| 摘要 |
PURPOSE: To improve the using efficiency of talking slots and to store these slots in plural slave units as many as possible without deteriorating the extension transfer function or the broadcast general calling function. CONSTITUTION: When the extension transfer is performed to a slave unit 2-2 while a slave unit 2-1 is kept in a line wire busy mode via a master unit 1, the unit 2-1 sends a holding request including a suspended call number to the unit 1 to hold the line wire and then an inter-slave unit direct talking mode is set. In this mode, the unit 2-1 calls the unit 2-2 to notify it of a call received via a line wire together with its suspended call number after an answer is received from the unit 2-2. Then the calling is cut to the unit 2-2. When the unit 2-2 calls the unit 1 with addition of the suspended call number notified by the unit 2-1, the unit 1 connects the unit 2-2 to the line wire kept in a holding state to secure a talking enable state only when the corresponding suspended call number is coincident with the suspended call number that is already informed by the calling unit 2-1. |
