| 摘要 |
PURPOSE:To expand properly a telephone system by providing a data exchange means for exchanging data between a key telephone system interface and a processor installed in the main device of the 1st key telephone system. CONSTITUTION:A standard telephone set interface 3 connects a trunk line inter face 7 of the main device 1 to the key telephone system interface 5A of the main device 1A, and the system can be expanded by connecting the main device 1 and main device 1A in serial. A transformer 52 is installed which is a joint means for joining a sound line 54 of the key telephone system interface of the main device to a sound line 54A of a cross point of the main device. In order to exchange data between a data line 55 of the key telephone system interface of the main device and a data lien 51 for extending from the processor of the main device, a data exchange means composed of a control part 50, hybrid circuit 49 and transformer 53 is installed. |
