High Quality Content by WIKIPEDIA articles! Comcast Digital Voice (CDV) is a telephone product offered by Comcast Corporation. Comcast offers CDV in both residential and business class and is packaged with Xfinity. It is similar to VoIP, but differs in that it operates on a dedicated server and assigns priority to the information sent over the CDV network, and also means that the information is not transmitted over the public Internet. On the HFC (cable) network, calls are placed into individual Unsolicited Grant Service (UGS) flows, based on DOCSIS 1.1 QoS standards.