PhoneRTC demo not working

I'm new to PhoneRTC and now having problems to get the demo project running. I followed the instruction from the following link:

https://stackoverflow.com/a/26411191

The turn server provided in the demo is not alive anymore. I changed it to a working one. Now I can get the demo project running. However, the communication cannot be established when trying to take the incoming video call. I'm not seeing any error/exception log.

Can anyone please help me with this?