Calls to the U.S. and Canada will be free for at least the rest of the year and calls to other countries will be billed at Google's low rates. For example, calls to the U.K., France, Germany, China, Japan - and many more countries will cost $0.02 per minute, Google said.
Dialing a phone number works just like a normal phone. Just click "Call phone" at the top of your chat list and dial a number or enter a contact's name.
If you have a Google Voice phone number, calls made from Gmail will display this number as the outbound caller ID. And if you decide to, you can receive calls made to this number right inside Gmail.
Google is rolling out this feature to U.S. based Gmail users over the next few days, so users will be ready to get started once "Call Phones" shows up in their chat list (users need to install the voice and video plug-in). Google promised to make the feature available to non U.S. based users too in the future.
For more information, visit gmail.com/call.