| 摘要 |
PROBLEM TO BE SOLVED: To speedily perform emergency alarm operation by sending the disconnection message of a line under using, when a release completion message is received from an ISDN line network, releasing the line under using for another terminal for analog line, originating a call to the destination to report again and sending a following alarm message, when the line capture of an alarm is detected. SOLUTION: When a release completion message is received, a control circuit 24 of the ISDN line relay device recognizes line closing, including the occupancy of a B channel for the other terminal for analog line and generates a busy tone by controlling a tone generating circuit 21. This is sent to the emergency alarm device. The emergency alarm device, which receives this busy tone, recognizes absence of response from a party, releases the line, and sets a standby state. Afterwards, the emergency alarm device repeats processings which include line capture, dial tone detection, dial number transmission and line release, while at a terminal adapter part, a disconnection message(DISC) is sent out.
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