That's what is happening to me too. Unfortunately, most of the time now. They are not concerned. LOL I have the worse time when it rains too.
We have trouble with one of phone lines at work when it rains but the phone company says as it under the road and not the direct link to the socket we would have to pay for them to dig the road to investigate. When they test the line from the exchange it is OK.
So struggle on with getting complaints that when it rains we do not answer the phone LOL