Since the Mobile device still can receive incoming calls the issue is not related to Mobile network coverage or registrations. Settings on the PBX or Mobile device are the probable cause. Perform the following checks:


PBX

Are the PBX settings for the device correctly configured? Consider the following components:
- Has the SIM card been created in the telephone exchange and linked?
- Is the mobile number linked in the telephone exchange?
- Call scenario settings such as time slots, linked extension, user, call forwarding etc.


Mobile device

Are there restrictive settings active on the mobile device? Consider the following settings:

- Is night mode active on the mobile device?

- Is DND active on the mobile device?

- Is Call Forwarding been been set up on the mobile device?

- Are contacts blocked on the mobile device?


In case the issue remains file a problem report.