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.
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.