Comcast has become the first U.S. cable operator to take on telecommunications providers in the cell phone market, having begun marketing the service to consumers in Boston.

The largest U.S. cable television operator launched the service in Boston and Portland, Oregon, earlier this month after a year-long trial, but is only promoting its "mobile access" service with television commercials and direct-mail drops in the Boston metropolitan area.

Time Warner's cable unit, the No. 2 U.S. cable operator, said it has made wireless services available to customers who request it in Raleigh, North Carolina, and Austin, Texas, and would start marketing in the cities in the first quarter of 2007 and to all of its other markets through the year.

Cox Communications, the No.3 U.S. cable operator, also expects to introduce wireless services early in 2007.

The three cable companies plan to use the wireless network of No. 3 U.S. mobile operator Sprint Nextel Corp. as part of an agreement reached last year.

Comcast is offering wireless as an add-on for subscribers of its "triple play" package of cable TV, telephone and Internet services. The price is $33 a month for 200 minutes and provides such services as voicemail, navigation and call forwarding.

Although the customer will receive only one bill for all services, Sprint will ultimately receive the wireless fees. The main benefit for Comcast is to attract and retain subscribers.

The company plans to introduce the wireless service into more markets in the next 12 months.

Consumers can pay an additional $15 to $25 a month for a range of entertainment content, including video clips such as local news and weather.

Time Warner Cable said its wireless packages start at $29.99 a month as an add-on service. Additional data services, including local news video subscription, will start at $15.