Momentum is building for services that let consumers make phone calls over the Internet. In 2005, the consumer market for voice over Internet Protocol, or VoIP, calling grew by more than 250 percent, with over 3 million people subscribing to a VoIP service, according to Yankee Group Research. This figure is expected to jump yet again in 2006, to a projected 8.4 million subscribers. And by 2009, there will be 28.5 million VoIP users in the U.S., according to the Yankee Group.
For the past couple years, VoIP pioneers such as Vonage and Skype have accounted for the majority of consumer subscriptions to Internet telephony services. But now other players, such as cable operators, are entering the market. Time Warner added 270,000 digital phone subscribers in the first quarter of 2006, its biggest gain ever. And Comcast, the largest cable provider in the U.S., added 211,000 new phone customers during the quarter, more than it had signed up during all of 2005.
Internet companies such as AOL, Google, EarthLink and Yahoo are also getting into the game with services that let PC users make calls not only between PCs but also from their computers to regular phones.

CNet