"Thanks to everyone using this new feature," the company tweeted.
The company unveiled Gmail's voice calling feature Wednesday. The feature works much like a normal phone, enabling users to click on the "Call Phone" tab in their chat box. From there, they enter a contact name or phone number.
Google's new Gmail effort is a direct slap to Skype, which has become the leader in the Internet phone service market.
"It could potentially be a big competitor to Skype, but Skype is already very well adopted," said Yankee Group analyst Zeus Kerravala. "The question is what will Google's voice give you that Skype doesn't. Right now, the only thing is that it's part of Google, but that's hardly a differentiator."
Skype, founded in 2003, isn't just a consumer service. Businesses turn to Skype to make video and voice calls over the Internet. Google, which for months has been trying to push its way into the enterprise, could well be looking at getting another bite at the corporate pie through Gmail's new voice feature.
Google is trying to lure in new users by making calls to anyone in the U.S. and Canada free through at least the end of the year. The new feature is being rolled out to U.S. users this week. A time frame for introduced the service in other countries hasn't been set.
Sharon Gaudin covers the Internet and Web 2.0, emerging technologies, and desktop and laptop chips for Computerworld. Follow Sharon on Twitter at @sgaudin or subscribe to Sharon's RSS feed . Her e-mail address is email@example.com.