| 摘要 |
PROBLEM TO BE SOLVED: To enable emergency report to be received even in the case of a DC call signal when a command stand is pausing due to system down or the like in such emergency report as 119. SOLUTION: When the command stand 6 is pausing due to system down or the like, a switcher 5 is set to the side of a system conversion means 8. When emergency report is made from a first telephone 1 in this state, a DC call signal S1 is transmitted from a switchboard 2, and is received by a DC signal reception section 8a of the system conversion means 8 through the switcher 5. When the reception continues for specific time, it is regarded as a normal arrival signal, the DC call signal S1 is converted to an AC call signal by a DC-AC conversion section 8c, a call signal S2 is transmitted from an AC signal transmission section 8d to a second telephone 9 for calling the telephone 9. After the off-hook of the telephone 9, the DC signal reception section 8a, the DC-AC conversion section 8c, and the AC signal transmission section 8d are set to through state, and the first and second telephones are in call state.
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