| 摘要 |
PROBLEM TO BE SOLVED: To provide an extension switch board capable of controlling external line calls from extension terminals to effectively utilize lines thereby reducing the entire operation cost of a private communication system, which can solve problems in a conventional extension switch that it hinders an emergency call with an external line when the frequency of external line calls is increased so as to increase an external line call charge resulting in increasing the operation cost of the entire system. SOLUTION: The extension switch is configured such that an external call management table 21 stores propriety of external line call by each extension terminal 3 and an external call upper limit time (T1) for one external line call, and external line call control means 12 references the external line call management table 21 when receiving a call request from an extension terminal 3, outputs a message of disabled external line call to the terminal 3 when the terminal 3 is a terminal whose external line call is not permitted to reject the external line call, or when the extension terminal 3 makes an external line call, the external line speech control means 12 counts a talk time (t1), a message output means 14 outputs a message 4 denoting the interruption of line to the extension terminal 3 in the case of t1>T1, and a communication control means 11 interrupts the line.
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