KEYPHONE SYSTEM SUPPORTING BOTH BELLCORE TYPE AND BT TYPE CLIP

摘要

The present invention discloses a key phone system having improved reception characteristics to process both a bell core type and a BT type CLI signal among caller information verification service (CLIP) standards. The CLI signal consists of a warning signal and the actual CLI information signal. In the case of the Belcore method, the warning signal consists of a RING signal. In the case of the BT method, the CLI signal consists of a polarity inversion signal and a subsequent warning signal. In the key phone system according to the present invention, by adding an electronic switch controlled by a CPU to the analog trunk line interface circuit, it is possible to normally process not only the bell core type but also the BT type CLI signal. ; Key Phone System, CLI, CID, Caller Information.