connectivity problems outside the USA with apple watch ultra when its standing alone

I looked a little bit more into Apple support and there's actually three different Iwatch Ultra models and they are all working in different regions of the world.Not one, Iwatch Ultra can work all over the world.

It's nice to close that chapter but ,I still can't send SMS connected to US cell towers, and yes ,it is a Iwatch Ultra that is bought in the US for this region.

Thanks for replying Syaoran!!!