As Google merged more things into Hangouts, Google +, SMS, video messaging, to create a unified messaging app it seemed only a matter of time and speculation before Voice became integrated as well. Nothing was forthcoming for a some months and Android users could only speculate and wait. The waiting is finally over and now they have joined. On the 12th, Google pushed out updates for Google Voice and Hangouts. Now you could use Hangouts to send and receive text messages using your Google Voice number. But there's more.
Google also released a new app Hangouts Dialer. The Hangout Dialer works through Hangouts and uses your Google Voice number to make phone calls. Essentially allowing phone calls from a tablet using wifi or LTE if available. This also allows you to use your phone's data plan or wifi connection to make phone calls or texts without using your plan minutes. The union is complete and the long awaited joining of Hangouts and Google Voice is complete. Google Hangouts is truly a unified messaging app.