After a flurry of court activity resulted in a brief delay, the national do-not-call list went into effect in early October. For a company, subscribing to the list is relatively practical: You can access up to five area codes for free, and each additional one costs $25 annually, up to a maximum of $7,375. Compared to a possible $11,000 fine per violation, that is pretty reasonable. However, if that is impractical for you for whatever reason, there are some things you need to know.

Many successful remodelers rely almost exclusively on repeat business. Under the new rules, if a past client is on the do-not-call list, you have 18 months from the date of last sale to contact them about future business without risking penalty. D.S. Berenson, of Johanson Berenson LLP, McLean, Va., a firm specializing in construction law, says that "date of last sale" is a fairly vague term, but to be safe, consider it the first date on any contract you sign for a particular project. This means, in some extreme cases, that the 18-month window may be closed before the project is even finished. You may call these clients at any time, however, to ask for referrals.

Berenson also points out that it's important to understand that "any call whose purpose is to induce the sale of goods or services is going to be considered a telemarketing call -- whether it starts out or ends up that way." So, while you're free to call a past client to ask how they like their new kitchen, if they're on the do-not-call list, you can't ask them if they want a deck built outside of it without risking $11,000.

Even if a person has expressed interest in the goods or services you offer, you can still find yourself in hot water if they've registered for the do-not-call list. The guidelines say that you can call them, without penalty, for 90 days from the time they make the inquiry. Of course, if they subsequently ask that you not contact them again, you must heed that request.

On the other hand, a person who has registered for the list can grant you permission to call them. There is no standard format, but Berenson says it must be "specific written authorization" that contains the telephone number the consumer is authorizing, as well as their signature. It may be best to have a legal expert help you in such a case.

The law also requires that you allow caller ID to identify your number when making a telemarketing call, although that won't go into effect until late January.

Regardless of what you might hear about appeals and the uncertainty of the list, odds are that these rules are here to stay, in one form or another. Failure to comply with them could mean a not-insignificant hit to your bottom line. For more information on the do-not-call list, go to www.ftc.gov/donotcall.