This problem just started. Incoming calls ring once and the caller gets a busy signal. When I answer, it is just a dial tone. If I grab it quickly, I can get the call. I have tried the outside access and it works fine. We have about 8 jacks in the house, dial up internet, and dish network. I have unplugged all lines and tried one at a time, still same problem. I bought new phones, still same problem. Any ideas? Verizon charges 90 bucks per 1/2 hour. That is highway robbery!

If you have problem at "D Mark"(box outside), it is their problem, and No Charge.
See if you have a test jack outside, and try there.

Thanks for responding, but since I made the post, I found the jack that was causing the trouble and unplugged the phone. Now it is working.

If you look inside the jack contacts, they are supposed to be gold, were they black/green?
If you replace the jack, you shoud replace line cord as well, likely has same problem.