Very good app for those who dont have inbuilt volte function, voice is clear doesnt seems that we are talking over internet, no delay in voice. app design is pretty much average have chat function which is good to send free sms.
I havent experienced anything enhanced with rich calling feature, many times call disconnects due to network disconnects frequently though app is good enogh to make free calls. very usefull for students and those who see their account balance frequently after every call.