Integrated VoIP calls not working?

[emporiky]

Hi guys, since the announcement of ios10 I've been excited that VoIP apps will receive fair treatment and will now be integrated in the OS.
Calls will appear on lock screen, instead of a small notification popping up.

However, having installed ios 10 PB 4 I still cant see this working with Viber or Facebook messenger.
Can anyone confirm that they have managed to get this working?

 

[leo.andres.21]

I think the feature is there, but you won't see it integrated until Facebook and Skype gets to push this update to the public, which is when iOS 10 is GM'd.