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

Band support wasn't what I was referring to.  Just because a device, like an Apple Watch, is sold touting features like standalone calling, doesn't mean those features will work on every network.  There are plenty of carriers out there around the world that do not support smart watches in standalone, meaning would be required to be tethered to a smartphone to work. iMessgae requires a data connection to work.