Hi!
If the application has been unloaded from memory, then when an incoming call arrives, a push notification with an “Accept” button appears. However, when you press it, an authentication window appears in Rocket.Chat (“Add server URL”).
To accept a call on Android, I have to:
1. Close this authentication window (unload Rocket.Chat from memory).
2. Open Rocket.Chat again from its icon — at this point, it is already logged in, as if nothing happened.
3. After that, a green “Accept” button appears inside the application, and I can press it to answer the call.
All of this has to be done within 30 seconds while the call is ringing.