Phone slamming is an unauthorized change in your long distance service. Unscrupulous marketers use a variety of deceptive techniques to change your carrier.
Some companies use sweepstakes entry forms while others slam customers at random.
The dispute can usually be resolved, but the time investment required to correct the problem can be costly. When signed and returned, it prevents your long distance service from being changed without your express written authorization. Check your phone bill each month. If your long distance has been switched, there should be a notice on the bill. If you've been slammed, ask your local phone company to switch you back to your preferred carrier.