The telephone as a television?
All information in digital is contained in packets (internal link). Voice, data, or video signal are in bits which the packets carry. (internal link) A digital communication device can be designed, therefore, to provide different digital services.
A recent AP article (external link, read this soon before this link dies!) says Comcast will soon merge its cable TV and internet offerings with telephony. By the end of the year "It expects to offer its digital phone service to 15 million homes. Voice packets will be given priority -- and traffic will be carried over Comcast's own network."
"Rian Wren, Comcast's senior vice president of telephony, says voice services will converge not only with computers but also with TVs. In the next 18 months, you'll start to see prompts on your TV for processing e-mail, voicemail or incoming calls. Eventually, you'll be able to handle that communications right through your TV."