The trial follows one of the hottest trends in telecommunications: delivering voice as well as data over the Internet protocol, or IP.
Despite its merits, the trial, which uses technology from Lucent and Motorola, is small, affecting only 25 Comcast cable subscribers in the Union, N.J., area.
A group of telecommunications companies has been racing to deliver quality voice over IP, among them Lucent and Cisco, but the Comcast trial is unique because it uses cable rather than a telephone line or corporate network.
Trial subscribers use cable to make calls from their telephones, to receive cable programming or to surf the Internet through a TV and PC.
Lucent is touting the technology's simplicity as its significance. Companies typically must deliver voice, data and video over separate networks. But using what Lucent refers to as CableConnect technology, cable companies can provide the disparate services over one network.
Comcast eventually plans to offer a full range of combined services, including notification of incoming email messages while watching TV.