Google has added the ability to make phone calls to its new Hangouts service and to the Hangouts interface in Gmail.

It has also improved the service, adding new features and has made phone calls to the US and Canada free for all users living in countries where the service is available. Google has said that it's rolling out the service to all users over the next couple of days.

Until Tuesday, Hangouts lacked the ability to make calls to phone numbers. Although voice calling was present in the Chat experience within Gmail,the Hangouts interface, which is currently optional, also did not feature the service.

To make voice calls to phone numbers, users need to simply need to look for the new "Call a phone" menu item in Google+ or press the phone icon in Hangouts within Gmail. They can then dial a number or select one from their Google contacts to make a phone call.

The updated voice calls service also includes the ability to add multiple phone numbers and video participants to the same call. Users can also play sound effects (like applause or laughter) with the Google Effects app when on a phone call.

Google has also said that future versions of Hangouts will integrate Google Voice more seamlessly.

It's worth pointing out that calls to Indian phone numbers are charged at 2 cents per minute and you'll need to add credit in multiples of $10 to your account in order to make phone calls, except for calls to the US and Canada which are now free. Previously, free calling to numbers in these regions was available only to users located in US and Canada.

Google had announced Hangouts, a unified messaging service that merged its various messaging platforms including Google Talk, Google+ Hangouts, Messenger and Google Talk for Google+, at the Google I/O event in May. However, it only offered text and video chat at the time of its rollout.