iMessage setup - phone number registered but not associated; 3 days left

iMessages setup shows my phone's registered number (xxx-xxx-x024) with message "This number is registered to your Apple ID but is not associated with this phone. You can keep using the number for iMessage and FaceTime until it expires." with action "Remove from iMessage and FaceTime".

My iPhone SE (2nd generation) has an eSIM with my primary number xxx-xxx-x024, and a card SIM with a travelers number. The travelers number has never been used for iMessages.

How do I associate my registered primary number with the phone?

iOS 16.1.2