System for setting registration mode for key telephone set

Claim 1

A key telephone system comprising a main unit including: a speech path switch for selectively switching between at least one office line and a plurality of key telephone sets; a plurality of calling processing interfaces connected between said speech path switch and said plurality of key telephone sets; an operating data memory for storing operating data required for operating said system; operation mode setting means for setting an operation mode of said system in one of a call processing mode and a data setting mode; and control means for controlling said speech path switch by referring to said operating data memory when data transmission is periodically performed with said plurality of key telephone sets through said calling processing interfaces in the call processing mode, and for updating contents of said operating data memory according to operating data externally input in the data setting mode, wherein said system further comprises a direct station selection interface for connecting at least one direct station selection console to perform periodical data transmission and first detecting means for detecting that first normal data received, after a periodic data transmission with said direct station selection console through said direct station selection interface is an abnormal transmission for at least a predetermined period of time is data unique to said key telephone set, and said control means controls said operation mode setting means in association with an output from said detecting means to change the call processing mode into the data setting mode.