(MONEY Magazine) – Before slamming your phone down when a long-distance carrier calls to describe its latest fee plan, be sure that you haven't gotten slammed yourself. Despite 1991 Federal Communications Commission (FCC) rules that require long-distance phone companies to obtain your permission expressly before signing you up, in the past year the FCC got more than 1,600 complaints about carriers switching, or "slamming," customers to their services without prior approval. One clever recent slam: Matrix Telecom, a Fort Worth long-distance company, invited people to sign up for a drawing to win a cellular phone and airline tickets. By entering, they were actually switching their long-distance service to Matrix. A lawyer for Matrix says that his company's policy is to "comply with all FCC requirements governing long-distance services." Here's how to avoid a slam or take action if you've been hit: -- If a long-distance rep calls and you don't want to switch services, say so. Get the name and phone number of the salesman, just in case. -- If you do get slammed, call your local phone company. That carrier can switch you back to your original long-distance service. -- Slam victims also should file complaints with the FCC (Enforcement Division, Common Carrier Bureau, Mail Stop 1600A2, Washington, D.C. 20554).