Hangouts has just been updated with Material Design and has finally gained integration with Google Voice. In addition, a new Hangouts dialer has been added to your list. If you were confused by the changes, read the article below for the latest Hangouts, Hangouts dialer, and Google Voice interaction.

Everything you need to know about Google Hangouts. ANDROIDPIT
Hangouts now make and receive calls
Google Voice, despite being a great service, has been stagnant for a long time. Its features have gradually migrated to Hangouts, and incoming calls have been supported for some time. The latest update added the ability to make calls, taking away almost all the functionality of Google Voice.
Hangouts
Google Voice is (almost) dead
Google Voice still exists as a standalone application, but is at risk of extinction. It won't be long before Hangouts completely encompasses it, and it will stop at the graveyard of apps that nobody else uses. Integrating all Google Voice functionality with Hangouts puts this app on a par with Skype, and is ready to compete with Microsoft's service.
International calls are cheap
Once you have the ability to make calls to Hangouts, you might want to consider Skype as an alternative to communicating with friends and family. The service offers very competitive rates for international calls.

The new lightweight, green, Material Design-based Hangouts. ANDROIDPIT
Hangouts has a new look
The first thing you'll notice is that Hangouts has the new Material Design, but it still has a very simple interface to use. We now have two active tabs and a side menu. Both tabs are for your contacts and messages: simple as that.
Archiving mode has changed
If you had the same problem as me, accidentally filing conversations, it's over: by sliding your finger you now change tabs. Google has removed the swipe to archive function from the new Hangouts. If you want to archive a conversation, just long click on a Hangouts inbox chat and an arrow box icon will appear. Or you can go to the conversation itself, click on the three point menu and select the archive option.