Dear Forum,

Yesterday, I was trying to troubleshoot my downstairs phone. My
upstairs phone works fine.

Downstairs, the phone line is in rather poor shape. The phone line
connects to a socket whose screws are corroded. When I jiggled the
socket, I got a tone. However, a few moment later, the downstairs
phone would not give me a tone. More surprising, the upstairs phone
would not give me a tone either. I had to wait about 10 minutes before
getting a tone upstairs.

Does anybody know what could have happenned?

I greatly appreciate your help.