Customers can make free domestic phone calls and send text messages at Wi-Fi hotspots.
But the app also supports mobile calling using 4G or 3G mobile data plans as well.
Customers also can send and receive text messages domestically and internationally to more than 40 countries, including Canada, Brazil, China and, soon, Mexico, Comcast says.
Xfinity Voice also now offers up to four "Personal Phone Numbers" that can be assigned to family members, and are separate from the primary account holder’s phone number.
One example is that a child can use an iPod touch to communicate, eliminating the need to subscribe to an additional monthly mobile service plan.
These features will be coming soon to new Xfinity Voice customers, so the business model is sales of Xfinity voice lines and retention of those customers, not ancillary revenue from use of the app.
The Xfinity Connect Mobile app can be downloaded for free on the iTunes Store or Android Market as well as online through Xfinity Connect.