iMessage not working from phone number

I recently turned off iMessage on my iPhone 7 and when I wanted to turn it back on, I got the 'Waiting for activation' message, which is constantly there. My phone number shows up in the 'you can be reached by etc.' menu, however it has a spinning wheel next to it. iMessages work only from my apple ID email address but not from the phone number. I also do not have the 'start conversation from' option in iMessages. All this applies to FaceTime on my iPhone as well.

I have tried every fix known to man, researched everything... in the end even did a restore, erase all content and setting, and the problem persists. I changed my apple ID password a few months ago, however since then activated iMessages successfully when I switched from an iPhone 6 to an iPhone 7, so I do not think that was an issue. However, I have now changed my apple ID password again and then signed out and signed in to all devices, apps, etc. and the problem is still there. When I log in to manage apple id, the phone number is there, however I cannot do anything to it (change, delete, etc.).

As mentioned, I already tried all the usual fixes, toggle iMessages on and off, sign out and sign in to apple id, turn on airplane mode, reset network settings, reset location settings... absolutely everything I found in various forums.

Does anyone have any idea on what else I could try? Perhaps get a new sim card with the same phone number (although cannot see what good that might to?)

Appreciate your thoughts... thanks