| 摘要 |
PROBLEM TO BE SOLVED: To provide a means for adding an extension extending function by which a phone connected to a fire-fighting station terminal can be used as an extension phone connected to a PBX in the fire-fighting station headquarters without the provision of an extension extending trunk. SOLUTION: A trunk call control circuit 2aa for applying call control to a phone 6 connected to the fire-fighting station terminal 5 via a command line L2 is provided in the inside of a command trunk 2a of a command controller 2 as an extension extending phone connected to the PBX 3 of the headquarters. When the phone 4 connected to the PBX 3 makes a speech with the phone 6 connected to the fire-fighting station terminal 5, the phone 4 informs the PBX 3 about the call and informs the command controller 2 about it via an extension line L1. Thus, the trunk call control circuit 2aa provided in the command trunk 2a of the command controller 2 is activated to inform the phone 6 extending the extension connected to the fire-fighting station terminal 5 via the command line L2 about the call from the phone 4.
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