Apple will be providing two separate cellular models of the Ultra that feature both LTE and UMTS band coverage. This goes for the Apple Watch SE and Apple Watch Series 8, as well. The firm notes on its website that the models have been "optimized for use in the country of purchase, and not all models work in all countries or regions."
Additionally, Apple announced amid the "Far Out" event that all new cellular Apple Watch models, and some older versions as well, will be treated with international roaming. From Series 5 and up, users will be able to utilize the international roaming feature, with up to 30 potential carriers being supported by the end of 2022.