Google has had many different messaging apps in the past, and they’ve done a good job in finally condensing that number down to only two, Hangouts and Google Voice. Google has integrated Google+ messaging, Google Talk, and even SMS into Hangouts, but Voice is still on it’s own. Android users have begged for the functionality but still haven’t received the functionality.
Google hasn’t officially announced dates on when this merger would occur except for saying that it was “months out”. This leads us to believe that it will be announced at Google I/O, possibly beside the Google Smartwatch. The functionality of VoIP calls in Google Hangouts could lead some users to completely drop their carrier voice plans altogether and simply rely on data. We would expect carriers to challenge that but we will have to wait and see what happens. This is expected to happen on all platforms including iOS, the web, and of course Android.