AT&T CallVantage was a VoIP

Voice over IP

Voice over Internet Protocol is a family of technologies, methodologies, communication protocols, and transmission techniques for the delivery of voice communications and multimedia sessions over Internet Protocol networks, such as the Internet...

 telephone service first offered in 2004 by AT&T Corp.

AT&T

AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services...

, upon the heels of its announcement that it would stop seeking traditional local- and long-distance land-line

Plain old telephone service

Plain old telephone service is the voice-grade telephone service that remains the basic form of residential and small business service connection to the telephone network in many parts of the world....

 customers.

After SBC Communications

AT&T

AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services...

 purchased AT&T Corp. in 2005 and merged into AT&T Inc., CallVantage was offered as an option with AT&T Yahoo!

AT&T Yahoo!

AT&T Internet Services is a d/b/a name for 5 companies that provide Internet service.-Companies:The following companies provide AT&T Internet service:*Ameritech Interactive Media Services*Pacific Bell Internet Services...

 DSL

Digital Subscriber Line

Digital subscriber line is a family of technologies that provides digital data transmission over the wires of a local telephone network. DSL originally stood for digital subscriber loop. In telecommunications marketing, the term DSL is widely understood to mean Asymmetric Digital Subscriber Line ,...

 service, formerly known as SBC Yahoo! DSL.

AT&T CallVantage had previously competed with other VoIP providers, such as Vonage

Vonage

Vonage is a publicly held commercial voice over IP network and SIP company that provides telephone service via a broadband connection. The company's name is a play on their motto "Voice-Over-Net-AGE"....

but suspended new business in 2008 while AT&T continues "to evaluate CallVantage service."
In a letter dated April 17, 2009, AT&T notified all existing Callvantage subscribers announcing the service would be discontinued at some point during 2009. It was later announced that the shutdown date would be October 20, 2009. AT&T's CallVantage service has been discontinued and is no longer available.