Ok, so I got a new LTE enabled galaxy watch last night (ordered direct from Samsung). I also have a Galaxy S9+ phone (also ordered direct from Samsung, unlocked, not AT&T branded). I've now spent 3 hours going back and forth to the AT&T store near work, and on the phone with AT&T tech support.
First they used a blue esim card to provision my watch. Ok, that worked. They told me how to set up numbersync. I tried that when I got back to the office and it gave a strange error. Called tech support, they came to the conclusion that my phone needed a new sim card. At the same time, they apparently disabled the esim for the watch Went back to the store, got a new sim card (the old one was almost 7 years old). Came back. Factory reset watch. Sim in watch still not provisioned. Called tech support again. This time the person realizes I have an unbranded phone.
I'm then told because I have an unbranded phone, they can't turn on voice over LTE, which is required for numbersync.
The unbranded GS9+ can do VOLTE on ANY OTHER NETWORK! So why can't AT&T enable it? And why is it required for numbersync?
At this point, I'm so frustrated that I just cancelled the new line for the watch. And i'm very tempted to switch to a different carrier at this point. I've been a customer of AT&T FOREVER (since the pre-Cingular and Cellular One days of 1992). How hard is it to make technology work?
Is there any way this is ever going to work with the hardware I have?
I feel your pain. Have the same problem now (had it before with another watch). I've been going back and forth since December with the reps who have told me that it should work anyway. Some folks here told me the same thing you are saying about the VoLTE issue.
So, okay,I tried the obvious fix. I switched phones to a branded phone purchased directly from the same store I got the watch.
Still get the same error. So deduce from that what you will.