I found what the issue was :Hi @WifxMain,
Could you please check the following:
- Chat notifications working?
- Is the app in silent mode?
- What appeared in Settings -> Advanced -> Notifications, Audio .... -> Ringtone Type?
- Device's OS version?
Thank you !We released today v18.0.8.82 Beta of the Android App today:
https://www.3cx.com/blog/change-log/3cxphone-android-build-history/
Please install this version and let us know if the issue resolved.
Tried the Beta - no change in behaviour. Still no ringing when phone is locked.We released today v18.0.8.82 Beta of the Android App today:
https://www.3cx.com/blog/change-log/3cxphone-android-build-history/
Please install this version and let us know if the issue resolved.

Founded in 2005, when VoIP was an emerging technology, 3CX has gone on to establish itself as a global leader in business communications.