PERMANENT CALL ALARMING SYSTEM

摘要

PURPOSE:To attain alarming without using howler tone, by calling an idle extension telephone set in a group to which an extension being in the state of permanent call belongs with a common control circuit, when the permanent call of the extension continues for a prescribed time. CONSTITUTION:When the permanent call of the extension A continues for a prescribed time, the common control circuit CC retrieves the group of the extension A and calls an extension A' by driving an extension circuit L' corresponding to other idle extension A' in the group and makes the connection of the route (2) by driving a channel switch TDSW. A prescribed signal tone or message is transmitted from an alarm tone trunk ANS to the extension A' so as to inform that the other extension in the same group is in the state of permanent call.