Swirling circle next to my phone number in "You can receive imessages to and reply from" box

There is a Swirling circle next to my phone number in "You can receive imessages to and reply from" box on my iphone 8+, version iOS15.5.

There are email addresses listed there, but when I try to add my phone number, it sends a verification to the phone number THAT IS NOT WORKING, so it is definitely a Catch-22 problem. I cannot add the number, I cannot receive the verification code. I am also locked out of my gmail account because the verification goes to that number that is not working.

I have spent 8+ hours trying to solve this problem now; I have set and reset and updated network settings and turned on and off the phone numerous times, but I need to get back to work! Can you help me solve this problem please?