Gmail's free phone service to numbers in the US and Canada has been extended until the end of 2011, according to the official Google Blog
. Introduced earlier this year, the "call phone" button lets US Gmail users dial any phone number using their Google Voice numbers. The service was already guaranteed free through 2010. Google hasn't announced what its eventual domestic rates will be or revealed any plans to extend the service to international Gmail users, but it now has another year to work out those details.