Make Phone Calls From Gmail

“

We’re rolling out this feature to U.S. based Gmail users over the next few days, so you’ll be ready to get started once “Call Phones” shows up in your chat list (you will need to install the voice and video plug-in if you haven’t already). If you’re using Google Apps for your school or business, then you won’t see it quite yet. We’re working on making this available more broadly - so stay tuned! 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.

Link