Comcast will not let you use your own equipment for voice (MTA) service. When you return their modem they will give you an eMTA (which is basically just a cable modem with an analog phone adapter ...

Each month, when your Comcast bill comes due, many of you pay a monthly fee for the device that provides internet access in your homes. Rental for what’s known as the Xfinity Gateway typically runs ...

This is the first time I've run across this, but I usually work with TWC and Verizon where as long as it is a supported modem they don't care (or they don't charge you for the modem). I can't believe ...