There is something wrong with the phone itself. According to the query of 360 personal databases, the fire telephone switchboard is usually under normal monitoring. Turn on the "power" switch located at the back of the fire telephone switchboard. If there are no input, output and fault signals, it is in a normal viewing state. The switchboard has 0 key, but there is no 0 key because the phone itself is faulty and needs to be replaced immediately.