Google released their unified messaging client Hangouts for Android, iOS and Chrome which brings several features. It is offered as an update to Google Talk for Android and allows iOS users to stay in touch with their Android friends. It even upgrades GMail chat and Google+ Hangouts but lacks one feature that users were really looking forward to - SMS support.The good news is Google has confirmed that SMS support is in the works and it will be available for Hangouts "soon".
This was confirmed by Google's Community Manager for Hangouts and Chat, Dori Storbeck who said: "SMS integration is coming soon - it is one of our most requested features!". It seems the code is already in place in the current client as users have confirmed that read and send SMS are listed in the Hangouts permissions page.
Storbeck also had the following to say about voice calls in Hangouts:
"This first version of Hangouts doesn't support outbound voice calls to mobile phone numbers, but calls into your Google Voice number can be answered in Hangouts. Future versions of Hangouts will support outgoing calls along with other Google Voice features".So it looks like Google Voice will also be fully replaced by Hangouts making the app truly universal. Also given that Google is generally quick with pushing updates for new products we should see the Hangouts update appear sooner rather than later.
We did run out own tests with Hangout on an iPhone 4, Nexus 4 and Motorola Xoom. The experience seems smooth overall, but we found the service crashing several times within GMail. Hopefully Google will iron out the kinks in future releases and it is likely that Hangout will be deeply integrated into the next version of Android.
source - +Dori Storbeck | +Kenny Strawn | PhoneArena