Advertisements for free Internet service offers are abundant. You may already have received a mailed CD-ROM promising hundreds of hours of free Internet access during a “trial period.”

The Federal Trade Commission and Northeast COMBAT warn that many “free” offers wind up being high-cost, long-term commitments because restrictions, conditions or obligations on these offers are not always disclosed clearly or conspicuously.

Most offers for free Internet service are valid for only one month. At the end of the free month, many Internet service providers automatically sign you up for their service unless you cancel at the end of the free month. You may not realize that you have to cancel because some ISPs hide this information or don’t tell you how to cancel.

Costs add up in other ways, too. For example, if you sign up for service and the ISP doesn’t offer a local access number, you’ll pay long-distance telephone charges to access the Internet. Some ISPs offer a toll-free (800, 888 or 877) number for an Internet connect. The FTC says consumers have been charged $5 or $6 an hour to use a “toll-free” number.

Ask the ISP the following questions about their service before accepting any free offers:

. Does free access to the Internet last longer than one month? Offers for an advertised 500 free hours of Internet service in one month would require you to be online for more than 16 hours a day to use all the free hours in a month.

. When does the month of free service start? Is it when you sign up or when you start using the service?

. Does the ISP automatically subscribe you to its service at the end of the trial period? Are you required to cancel before the end of the trial period to avoid being charged for service?

. How do you cancel service – online or by calling the ISP’s phone number?

. Is there a local phone number for Internet access? When you get the access number from the ISP, ask the phone company if it’s a local or long-distance number. Make sure the backup access number is local, too. If you have to call long distance for Internet service, you will rack up big phone bills.

. If you sign up for service, are you committing to pay for a year? Longer? Some ISPs require you to agree to pay for service for at least one year and may charge a fee to cancel the service before your subscription has ended.

. If you sign up for service, when are you billed? If you decide to cancel service, you may want to do so before your billing date so you don’t incur a monthly charge for service you don’t plan to use. Remember – ISPs bill you before you use the service.

. If you cancel your service, does the ISP send you a notice? If you do cancel, get verification (e.g., confirmation number) that your account has been canceled and check your next credit-card statement to make sure you aren’t still being billed by the ISP.

If you think you’ve been misled about an offer of free Internet service, contact the FTC or Northeast COMBAT through Consumer Forum.

COMBAT is raising funds to create a Maine Center for the Public Interest to provide Maine residents consumer information and assistance on the Internet. If you would like to be notified when the Web site is activated, e-mail NeCOMBAT@aol.com (under construction and not currently available for inquiries).