Please include following information for better support

What version of React Native are you running?
What version of react-native-twilio-voice are you running?
What device are you using? (e.g iOS9 simulator, Android 6 device)?
Is your app running in foreground, background or not running?
Is there any relevant message in the log?
If using iOS, which pod version are you using?

Step to reproduce

Advanced:
Have you tried adding break point in native handlers and see the logs printed?
can share a project with issue?
Did you try to reinstall the pods completely?

The more context you provide around this issue the faster the community can help you.