iPhone 14 pro verification error message

Why is my iPhone 14 Pro stuck in a ‘waiting for activation’ loop which then changes to an error message (‘Activation unsuccessful. Turn on iMessage to try again’). I did turn iMessage on & off many ways and I’ve also tried everything else posted in various forums and have all the settings/passwords etc. correct…simply trying to switch from my iPhone X! I followed the exact same steps to switch my partner’s iPhone X to a iPhone 14 Max with no issues…we are both on the same wireless plan with no problems with our carrier or our wi-fi….please HELP! (BTW, we both also received new SIM cards from our carrier and installed them without a problem, but again my partner’s phone switch went smoothly while mine continues to say ‘waiting for activation’ no matter how many times I try to re-set, re-boot, etc etc. Is this a problem with the 14 Pro specifically? I paid waaaaaay too much money for this upgrade to be having these glitches!)