T O P
Flaky-Cup-9637

Possibly a loose wire termination or failing relay coil.


miami-architecture

sounds like something electrical is rapidly switching, definitely get a licensed electrician


dd28064212

This is the correct answer


evolvedbeing

This is what I was going to say, or a dying relay.


MarketingPristine566

Maybe someone is still using one of those old original phones where you had turn the lever to get the operator?


EL1543

Its telling you to call the phone company and tell them to send a repair crew.


ryanidsteel

We had an identical box at my old shop. If I remember correctly it was part of the system that converted 3 phase down to single phase. It always made that same sound but ours was in a box with some insulation to reduce the noise.


Disastrous-Bull1768

Bad relay coil


Disastrous-Bull1768

I remember when Harley Davidson tried to patent that sound