Your European Apple Watch won't work with a U.S. carrier

It appears that if you're looking to get the cellular version of the Apple Watch Series 3, you'll need to get it in your home country if you hope to use the LTE networking. While the watch works with several LTE bands used around the world, it appears that it does not support roaming between carriers in different countries, even between countries in which the same model is sold. Additionally, the watch does not appear to allow cellular use between different regions, i.e. an Apple Watch purchased in the U.S. will not work with cellular networks in Europe.

This information comes from Apple Support via Reddit user learnjava:

  • The watch will not support roaming. At all. For Europeans that means your country only, even after the recent (June) law about European roaming freedom.

  • There is no way to use a European watch with e.g. a US-carrier. The hardware might support identical bands (but even then way different than what we are used to from iPhones) but the service rep told me that it is not clear when and if at all it will be possible to change countries. Could be a hardware limit.

learnjava later went on to clarify his original post:

You mix together two issues. First is that different regions have different frequencies and the watch does not cover all of them so yes, like ten years ago. [sic]

Second issue is that even between countries in the same region, roaming is not possible. So I can not use my German watch with my German plan in France even though both countries are sold the same model. I need a French plan for that.

It appears that you might (and I stress might) be able to use the cellular networking features on other carriers within your region as long as you're willing to switch cellular plans, as this doesn't seem to be the result of any sort of carrier-locking policy. However, that would likely require you to change your iPhone plan as well, because, at least in the U.S., Apple Watch cellular service is tied to your iPhone's current service plan.

However, if your carrier works in multiple countries within your region (such as Verizon operating in both the U.S. and Puerto Rico), it's likely that your watch will work on that network across borders. We will, of course, need to wait for the release of the watch to know this for certain.

Apple Watch model Country LTE Bands UTMS bands
A1860, A1861 U.S., Canada, Puerto Rico 2, 4, 5, 12, 13, 17, 18, 19, 25, 26, 41 800MHz, 850, 1700, 1900
A1889, A1891 Austraia, France, Germany, Japan, Switzerland, U.K. 1, 3, 5, 7, 8, 18, 19, 20, 26 800MHz, 850, 900, 2100
A1890, A1892 China 1, 3, 39, 40, 41 2100 MHz

There are a couple of things to note about this. First, the issue of a lack of roaming between countries in the same region could change in a software update down the line. However, just as with the issue of region locking (which is likely more of a hardware limitation), it seems probable that we will need to wait for updated watch hardware for it to be resolved. It should also be noted that, compared to the iPhone, the Apple Watch Series 3 supports relatively few LTE bands, which could be a contributing factor to these issues.

In the meantime, note that this obviously only applies to the cellular networking aspects of the Apple Watch Series 3. When connected to your iPhone, your new Apple Watch will function as it normally would, and will be capable of everything that an iPhone-connected watch can do, no matter what country you're in.

Yes, you can buy Apple's GPS + Cellular Apple Watch and use it without LTE