Or, if it is feasible, call your phone company and tell them to disconnect the long distance service from the line that your computer runs on (assuming you have a regular line and one that is just used for the computer). That way the call can never go through. I had a problem with the same thing not long ago, and the disconnection of long-distance saved me a few times, since I have my modem speaker turned off, and can't tell if it disconnects and redials suddenly.

Ouroboros