TELEPHONE ADAPTER

PROBLEM TO BE SOLVED: To provide a telephone adapter capable of making a apparatus appropriately recognize faults occurred in a line, wherein the apparatus should recognize the faults. SOLUTION: The telephone adapter is connected at ISDN lines which couples a central office side exchange to a private branch exchange or a telephone device. While an ISDN line from the office side exchange is connected to the telephone adapter, an ISDN line from the private branch exchange or the telephone device is also connected to the telephone adapter. If the telephone adapter detects a fault occurred in the ISDN line connected to the central office side exchange, the telephone adapter disconnects electrically the ISDN line connected to the private branch exchange or the telephone device. Moreover, if the telephone adapter detects a fault occurred in the ISDN line connected to the private branch exchange or the telephone device, the telephone adapter disconnects electrically the ISDN line connected to the central office side exchange. COPYRIGHT: (C)2007,JPO&INPIT