NEW YORK — MobiTV Inc., which provides TV services on Sprint Nextel Corp. cell phones, is trying to shut down a Web forum that is carrying instructions on how to get access to its channels for free.

MobiTV sent a letter to www.Howardforums.com, asking the site to take down links that provide MobiTV streams from Fox News, MSNBC, Animal Planet and other networks when entered in the Web browsers of certain phones.

After Howardforums refused to comply, MobiTV sent a letter Thursday to the site's Web host, Atlanta-based Global Net Access LLC, asking that it shut down Howardforums.

The letters were provided to The Associated Press by Howard Chui, owner of Toronto-based Howardforums.

Calls to MobiTV and Global Net Access were not returned. The site was still up on Friday afternoon, and Chui said Global Net Access had not been in touch with him.

Sprint charges $9.99 per month for access to 100 MobiTV channels.

Toronto-based www.Howardforums.com has 795,000 users, of whom 200 are paying, according to Chui. It is focused on cell phones and cell carriers.

In an e-mail, Chui said he has complied with cease-and-desist letters from copyright owners before, when users posted pirated software. But in this case, he said, the posting just contains links to MobiTV's Web site, which is accessible to anyone on the Internet.

"These feeds do not appear to be protected in any way, and it appears anyone with a compatible phone can view them," Chui wrote in a posting. He questioned why MobiTV was operating its service without authenticating its subscribers.

A MobiTV lawyer responded that the specific MobiTV Web address was obtained in violation of the company's intellectual property rights, Chui said.