Treatment method:
The inspection system whether the interference source, the audio line is connected;?
The check intercom host and extension is faulty, the host may be the speaker and microphone has a problem;
You can also adjust the volume and other related methods.
* Note: strictly in accordance with the relevant provisions of the weak current system, and according to the requirements of the system specification wiring, far away from the strong electricity, it is best to use the shielded wire.