Comcast Corp.'s new cellphone service is now available in all its U.S. markets, the company said Thursday.

Comcast launched Xfinity Mobile — which the company says can save consumers 30 percent on wireless bills — earlier this year to its employees and in select markets including Philadelphia, reselling Verizon Communications Inc. wireless spectrum and utilizing Comcast's 18 million WiFi hotspots.

The company said it would take the service nationwide quickly, which it has now done.

"We have created a unique mobile experience that's simple and saves money by connecting to our nationwide WiFi network and allows [customers] to only pay for the data they use," Greg Butz, president of Xfinity Mobile, said in a statement Thursday. "Now that we're available across all of our distribution platforms, including our retail locations in all of our markets, we look forward to introducing even more customers to Xfinity Mobile."

Analysts believe that Comcast and Charter Communications Inc., the two largest cable operators, have to offer mobile services to remain relevant to younger consumers looking for streaming and other data services to access through their smartphones.

There has been speculation by analysts that Comcast could acquire Sprint, T-Mobile, or even telecom giant Verizon. But in his company's earnings conference call last month, Comcast CEO Brian Roberts pooh-poohed the speculation about a deal for a wireless firm, noting the difficult economics in the highly competitive sector.

Comcast did, however, purchase $1.7 billion in wireless spectrum in the latest Federal Communications Commission auction that reallocated spectrum from broadcast TV stations to wireless services.

Sprint and its corporate parent, Japan-based Softbank, also have been linked to a potential deal for Charter. Charter has said it will launch its own mobile-phone service in 2018 in a strategy similar to Comcast's, also using Verizon wireless spectrum. On Thursday, Charter did not provide any additional information about its wireless plans.

In these early days, Comcast has not released any subscriber information on Xfinity Mobile users, but company officials say they are pleased with its introduction. Xfinity Mobile is  available only to Xfinity Internet customers and cannot be purchased as a stand-alone service.

Comcast says Xfinity Mobile costs $45 a month a line with no unlimited data usage, though speeds are slowed after 20 gigabytes. Customers also can buy individual gigabytes of data for $12.

Xfinity Mobile subscribers are billed separately for their mobile services, as Comcast has attempted to make it an all-digital experience in which people order phones online, adjust their data plan online, and pay online.