Google is obviously very invested in Google+ right now, and one of the ways they are trying to push it is with Hangouts. Last week they showcased Hangouts in a video for the Galaxy Nexus, and also in a TV commercial during the Lions/Packers Thanksgiving Day game. Now they’re introducing another feature to hopefully pull in more users: voice calls.
Say you’re in a Hangout with some of your friends and you want someone else to join. Unfortunately they don’t have a Galaxy Nexus and they aren’t at a computer. What do you do? Simple. Now you can dial there number and call their phone so they can join the Hangout via voice. That’s all you have to do to set it up. There is no need to have a Google Voice account unless you want to make calls overseas.