Google Voice is a telecommunications service by Google launched on March 11, 2009. Google Voice had some 1.4 million users in October 2009, 570,000 of which used the service 7 days a week.
The service is configured and maintained by the user in a web-based application, styled after Google's e-mail service, Gmail. Google Voice currently provides free PC-to-PC voice and video calling worldwide between users of the Google Voice and Video Chat browser plugin (available for Windows, Intel-based Mac OS X, and Linux), and free PC-to-phone calls into North America (this service will remain free at least until the end of 2011).
Mobile phone applications
Google Voice applications for Google Android, BlackBerry and iPhone can automatically place outgoing calls via the user's Google Voice service.
Google Voice does not officially support SMS to phone numbers outside of the United States.