My son tried to download some gaming hints online, but instead he got a self-installing program that dials out for access to porn sites. Then our phone bill showed two calls to Guinea-Bissau in West Africa costing $118. I explained to AT&T that this was a fraudulent charge. No one at our house physically dialed the number; our computer did. But AT&T insists that we made the call, so we have to pay. After some research, I found that many others have been taken in by this scam and have had to pay substantial bills to AT&T.

Steve Traylor, Eugene, Oregon

On Your Side responds: Shady Internet operators use seemingly benign sites to lure people into downloading programs that automatically dial overseas adult sites. In many cases, the mention of the dialer and what it does is buried in legalese that few users labor through. The unscrupulous sites have arrangements with their local telephone companies to take a percentage of the fees, explains AT&T spokesperson Bob Nersesian.

What can you do? Block access to international calls. But beware that some dialer programs have a workaround. According to AT&T, they use access codes to make local or international calls through carriers that may not be your chosen provider. Install a utility, such as Ad-aware 6 or Spybot Search & Destroy (available as free downloads), that will detect and delete unwanted programs.

AT&T eventually reversed all of the charges, according to Traylor. If you're an AT&T customer and you believe you have experienced this type of Internet scam, call 800/222-0300. Although AT&T will investigate billing issues on a case-by-case basis, Nersesian says AT&T doesn't police telephone fraud. For that, customers should contact the Federal Communications Commission.

Grace Aquino is senior associate editor for PC World. E-mail her at consumerwatch@pcworld.com. Click here to read more On Your Side column.