Check whether the phone is powered on and whether the line is actually connected and outputted. I think your problem must be the + -/+ - connection in the wiring. If the + -/- + phases are short-circuited
it will not work
It may be reversed or short-circuited. Pay attention to the color of the wire. This may have damaged the phone.
It is better not to connect two telephones in parallel directly, but to use a splitter, otherwise the two telephones will interfere.
After answering the extension, there is no ringing sound on both phones. The judgment is as follows;
First remove the indoor connection cable of the extension and see if there is ringing sound on the host. If so, it proves that the connected phone is connected. There is a short circuit in the extension line or extension phone. At this time, you can swap the extension with the host to see if there is a ringing sound from the extension. If so, there is a short circuit in the original extension line. To do this, simply change the extension line. If there is no ringing sound from the extension after the exchange, the extension phone is faulty and the extension needs to be replaced. It is worth noting that if the host still does not ring after removing the indoor extension lead, there is a short circuit from the telephone line to the telephone connector or a broken circuit.
Special reminder; the two incoming lines have no polarity and can be connected at will.
The telephone line is passed through an anti-interference device and a box similar in size to a matchbox, and then connected to the telephone , such as the solder joints of the small transformer in the anti-interference device are soldered, which will also cause the phone to be silent. At this time, you only need to repair the solder joints. .
First disconnect the extension, take it to the incoming line of the telephone line, and connect them separately to see if they are all normal (purpose: to eliminate the fault of the phone). If they are all normal, try again at the same place. Connect the extension and try (Purpose: to eliminate wiring errors). If it is still normal, finally take the extension to a different place and try again (Purpose: whether it is a fault of the newly added line). In this way, check one by one to find the fault and narrow the scope of the fault. .
Hope I can give you some help