Albaurmet.com — video door phone ringing outside only

Address:

Pune, Maharashtra, 411036

Hi Team,

I am having issue with the video door phone past two weeks. whenever someone rings the bell from outside the sound of the bell is heard from outside only, the bell sound does not come from the instrument place inside house. I have done a basic R & D of removing of power cable but that didn't resolve the problem.
The engineer which was assigned by the builder visited and checked all the wires and said he will try to change the cable / Plug and then check again, however he has not come back till date 16th Mar'19

could you please let me know how can this be resolved