Most calls don't connect Nice ui  but the messaging/call part is inconsistent  mostly not working. Using SIP as backend is bad idea because it is ineffective p2p. And please do not mention upnp as solution because that is an insecure setting that the user cannot always control and is not applicable to mobile data and many other scenarios. The only working scenario was on the same lan or vpn(although on Android vpn via mobile data wasnt working either regardless of manual setting of the vpn device). Also the phone was very hot 
November 05 2016