Component of bus wire telephone system, configured with TC3036 fire telephone panel.
Dialing switch is preset of 7 digits, ranging 1 to 99.
Connected to the panel through non-polarity two bus system.
When calling the panel, plug telephone extension into the jack will call it.
This device can be expanded and parallel to several jacks, the maximum amount is 7 and the total parallel jack amount in one system cannot be more than 30