SAN JOSE, Calif. — Google is offering the ability to make and receive phone calls on a Web browser from Gmail — putting the Mountain View, Calif., Internet giant into competition with online phone services such as Skype.

According to a post Wednesday on Google’s official blog, the Gmail phone service will roll out to U.S. users over the next few days. Calls to phone numbers in the U.S. and Canada will be free “”at least the rest of the year,”” according to the post. Gmail users also can purchase credits $10 at a time to place international calls, with rates starting at 2 cents a minute.

“”We’ve been testing this feature internally and have found it to be useful in a lot of situations, ranging from making a quick call to a restaurant, to placing a call when you’re in an area with bad reception,”” Google software engineer Robin Schriebman wrote.

According to the post, Gmail users who have a Google Voice phone number can receive calls through the e-mail service. Gmail users must download Google’s voice and video plug-in to their Web browsers to make or receive calls.