Google said the new service, which has rolled out this week, is free for calls to the U.S. and Canada at least until the end of the year, though there are costs to make international calls to landlines and mobile phones.Google Voice
Google said it hoped to later offer the service to international Gmail users and possibly to businesses.
For Google, the move helps drive users to Gmail as well as the potentially to add a feature to its software for businesses, called Google Apps. More than 200 million people currently use Gmail actively.

The move is Google’s latest foray into the telecommunications industry. Two years ago, Google launched a feature that allows Gmail users to do free video chats with other Gmail users. The company has also launched its Android operating system, which powers dozens of mobile phones made by Motorola Inc., HTC Corp. and others. It also backed a Google-branded phone made by HTC Corp., which has been discontinued.

Gmail users who have a Google Voice account can also receive inbound calls in Gmail, the company said. Google Voice is a free service that gives callers a new phone number that can be used to ring different real-world phones they own and can send them an email transcript of voicemails they received, among other features.

From my point of view the call quality is as good as my at&t cell phone :-{ and works great. If you don’t have a Google Voice number yet I recommend you run out and get one. Also, don’t forget the plugin….