April 23 (Bloomberg) -- Comcast Corp. and Time Warner Cable Inc., the biggest U.S. cable-television providers, are pulling out of a service they operated with Sprint Nextel Corp. to combine wireless calling and TV service on one bill.

Customers of the Pivot venture will move to Sprint's regular mobile-phone plans, Sprint spokeswoman Melinda Tiemeyer said in an interview today. The companies are still discussing ways to add wireless service to cable TV offerings, she said.

Sprint, Comcast, Time Warner and two other cable companies announced last year they would spend a combined $200 million to develop Pivot, aiming to compete against rivals including AT&T Inc. and Verizon Communications Inc. that offer mobile-phone service along with TV, home Internet and voice lines.

Comcast, which offered Pivot in New England and around Portland, Oregon, stopped taking orders for the service yesterday, spokeswoman Jennifer Khoury said in an interview. She said the decision was reached jointly with Sprint.

``We both decided that the product that was designed was too operationally complex -- dependent on too many companies to be a national, scalable product,'' Khoury said.

Comcast, based in Philadelphia, fell 15 cents to $19.76 at 4 p.m. New York time in Nasdaq Stock Market trading. Sprint, in Overland Park, Kansas, rose 62 cents, or 8.8 percent, to $7.67 on the New York Stock Exchange. New York-based Time Warner Cable fell 58 cents to $26.04.

Time Warner Cable

Khoury declined to say how many Comcast customers use Pivot. The financial impact was ``not material,'' she said. Comcast is the largest U.S. cable operator.

Time Warner Cable, No. 2, stopped signing Pivot customers months ago and will help users transition to a product offered solely by Sprint, spokesman Alex Dudley said in an interview.

Tiemeyer wouldn't discuss specifics of Sprint's discussions with cable providers.

``We're continuing to discuss various options,'' Tiemeyer said. ``Obviously Pivot didn't provide the long-term wireless solution that was needed.''

Pivot customers who move to Sprint's regular service will have 30 days to decide whether to remain or leave without paying a termination fee, Tiemeyer said.

Cox Communications Inc., which offered Pivot in six markets, is also dropping the service, spokeswoman Jill Ullman said in an interview. Sprint's Tiemeyer declined to say whether Bright House Networks, the other cable provider in the venture, would continue the service. Bright House spokeswoman Lorelie Johnson didn't return a telephone call seeking comment.

Wireless Network

Comcast and Time Warner Cable were in talks last month to provide as much as $1.5 billion for a new high-speed wireless network to be built by a Sprint venture with Clearwire Corp., according to people familiar with the conversations. Tiemeyer declined to say whether that plan is still under discussion.

Sprint also provides cable firms technology to offer Internet-based phone service to about 3.3 million customers.

The company stopped expanding Pivot to its retail locations in November after reaching 33 markets, or about 20 percent of its stores. Sprint halted Pivot sales in stores in February after finding the process of adding customers too complicated, Tiemeyer said.

To contact the reporters on this story: Crayton Harrison in Dallas at tharrison5@bloomberg.net; Todd Shields in Washington at tshields3@bloomberg.net

Last Updated: April 23, 2008 18:28 EDT