Comcast's Xfinity Home Security service has even more subscribers' backs now that it has been launched in additional markets across the nation.

The service, which first launched in Houston last year, is now being rolled out in parts of Comcast's hometown of Philadelphia and in Portland, Ore.; Jacksonville and Sarasota/Naples, Fla.; and Chattanooga and Nashville, Tenn. – with more markets to follow.

Xfinity Home SecurityXfinity Home Security offers traditional home security components, such as police and fire alarm protection, as well as the ability to adjust digital thermostats, turn lights on or off, and watch secure live streaming video from wireless cameras while away from home. The broadband-based service also comes with a new Xfinity Security app, which is available for free on Apple's iTunes App Store.

"Xfinity Home Security brings digital home monitoring to a new level," said Mitch Bowling, senior vice president and general manager of new businesses for Comcast Cable. "It comes with a range of broadband-based technologies that empower customers to stay better connected to their home virtually anytime, anywhere."

Xfinity Home Security offers Comcast customers the ability to create personalized settings that can do things like provide real-time email or text alerts when doors open or close, or when motion detectors report activity occurring inside or outside of the home. In addition, the service comes with a tablet-like touchscreen with a menu of widgets that allow access to the latest weather, news, traffic and sports scores.

The security service also ties in with existing Comcast offerings, including the ability to listen to Comcast voicemail messages through an app on the security interface.

Comcast's security service is another way of adding incremental revenue to its bottom line. The nation's largest cable operator is selling its Xfinity Home Security Preferred Package for as low as $39.95 a month. Users of the service could also receive up to 20 percent off of their homeowners' insurance.

Suddenlink also has a security service for its subscribers, which originally made its debut 30 years ago in some Texas communities.