iPhone Voicemail Greeting Error 1034

Recently my IPhone 15Pro Voicemail Greeting screen stopped working. When click on it says “retrieving greeting” , never stops, and then get “The operation couldn't be completed(com.apple.mobilephoneerror 1034.). I have spent hours with ATT advanced support. They say it has nothing to do with them. Just got off phone with Apple support tech and they say it’s ATT. My other IPhone 8 running IOS 16 has no SIM card, is not online, takes 15 seconds to say “retrieving greeting”, and works perfectly. I believe it is 100% an IOS 17 issue, Apple does not believe it. So now I’m stuck with the default greeting. Can anyone offer a solution? Thanks.