This could be a wiring problem or a problem with the phone. Try another phone (with new cables). Check the phone at another jack if you can. Find where your phone service comes in and check the connection type. If it is an RJ-11, plug in your phone at this connection and check for the problem on both lines (if you have true separate lines and not the distinctive ring feature). If it isn't an RJ-11, you will need your provider to check the phone line there.

If the busy signal occurs at the service connection, your phone company should fix the wiring for free (since it is on their side of the connection). If only the one phone is a problem, replace the phone. Otherwise, check all the exposed wiring and open the jacks. Check that the wires are fully seated in the jack or screws. If it isn't the jack or an obvious damaged wire, but an interior wiring problem, you need to check all of the wiring. Your telephone provider will do this for a fee. If your phone service connects to a DSL line, check the filters.

I hope this helps.

Cindy Wells
(I use an old rotary phone for phone line diagnostics. The unit isn't likely to have any problems that complicate tracking down a problem. I've had to run these diagnostics many times: mice damaged wires, contractor digging issues and surge damaged filters have all needed to be fixed in the past.)