"This number is registered to you Apple ID, but is not associated with this phone. You can keep using the number for iMessage and FaceTime until it expires."
I recently ported my phone number from carrier T-Mobile to carrier Xfinity on my same phone (14 Pro Max), and I got this text message. Xfinity uses an eSim so I did not have a physical SIM card to change, it was handled electronically. I have no idea what this message means or what I need to do to make sure this number, which I've had for years, is my number for both phone and messages.
I don't know if I need to get support about this with Apple or with Xfinity, or both.
There was one other support inquiry about this but it was regarding an international issue and a physical SIM card. So this is a different situation.