DENVER -- Colorado's no-call list, designed to protect consumers from telemarketers, may not help those who need it most because it is an online-only service, consumer advocates say.

The list was created in legislation approved earlier this year. People who add their names to the list can only make complaints about telemarketers who still contact them by using the Internet. The list was set up as an online system because lawmakers worried that other methods would be too expensive to administer.

Residents can add their phone numbers to the prototype list, which can be found on the Internet at www.coloradonocall.org.

That means thousands of consumers who have already signed up on a preliminary no-call list and who the attorney general says are the most vulnerable to telemarketing may be left without a way to complain.

"We don't have a computer," said Walter Uhrig, 82, of Aurora. "It would be a problem."

"Limiting it to e-mail only does make it very difficult, especially for the senior constituency, to make good use of this wonderful law," said Jon Looney, Colorado director for AARP. "Internet-only would cut out a lot of folks."

National and Colorado surveys show that the rate of Internet connection drops off sharply in the over-65 age group, and among the lowest-income families.

The Public Utilities Commission -- which is writing the rules that will implement the no-call list by July -- is not happy about the Internet-only restriction, said spokeswoman Barbara Fernandez.

"This requirement will make it difficult for a large number of Colorado residents who do not have ready access to the Internet to complain of violations," the commission's proposed rules said.

Providing a toll-free complaint line with live operators might force the state to charge consumers to get on the list, something supporters wanted to avoid. The PUC is restricted by the legislation, which requires the list to be put in place as cheaply as possible, Fernandez said.

The PUC is looking for a private company to administer the list and asking for suggestions on creating an easy method to complain for those who now would be shut out. The PUC could still change the rules before July if it finds a good idea.

The PUC also wants local phone companies, which opposed the no-call list because they use telemarketing themselves, to advertise the list's existence and show customers how to get their names on it. That demand is not in the original law, but the PUC believes it can require it.

"That would certainly be an effective way to let even more people know about it," said Peggy Lamm of the Bighorn Center, which helped conceive and lobby for the no-call list. Even without that help, more than 230,000 Colorado residents have already signed up for an informal list that the Bighorn Center will turn over to the eventual administrator.