Data search method in key telephone system
Data transmission system of key telephone system
Data transmission system of key telephone system
Dealing call terminal device
Dealing communication system
Device for communicating a doorside intercom set with a remote t
Device for detecting operation state of telephone hook switch
Digital button telephone system and extension terminal for...
Digital key telephone connecting apparatus and method in a digit
Digital key telephone set and digital key telephone system
Digital key telephone system and extension terminal device...
Digital key telephone system and extension terminal device...
Digital key telephone system and extension terminal device...
Digital key telephone system and extension terminal device...
Digital key telephone system and extension terminal device...
Digital voice conferencing bridge
Diverter interface between two telecommunication lines and a sta
Door intercom
Dual line adapter for telephone answering machine