Today Google announced that Google Voice is finally being integrated with hangouts. Google Voice has not received any attention in a very long time, and even though hangouts for iOS has supported free VOIP (WiFi) for quite some time, Android users have never gotten an official VOIP app until now.
The new Hangouts Dialer requires Hangouts version 2.3 which is being rolled out now, so all devices should be updated within the next few days. The hangouts dialer now allows you to make and receive calls from your Google Voice number. Making calls anywhere in the US and Canada are free. For those of us trying to save on minutes, or even if you just have poor mobile signal in a building, but have WiFi access, this is a great (and long awaited) feature.
Hangouts also has some nice user-interface changes that are more in line with the new material design guidelines. If you can’t wait for Hangouts 2.3 to be pushed to your device you can download and sideload a legitimate signed APK from Mega or Mediafire via AndroidPolice.
Unfortunately, it seems that texting (to and from your Google Voice number) is not supported. SMS and MMS texting is now officially supported.