I was under the impression that if you roamed the number share part stopped and the watch relied on connection via bluetooth. https://www.optus.com.au/shop/support/answer/number-share-what-you-need-to-know?requestType=NormalRe... This part: Can you use the Apple Watch GPS + Cellular overseas? You can take your Apple Watch GPS + Cellular overseas but it won't be able to Number Share and connect to a Mobile network. If you use your Postpaid Mobile Phone overseas, standard international roaming rates will apply. Now I dont know how "solid" apples implementation of data roaming switch as I think location data still is requested. But if you dont have roaming enabled on the phone service itself your safe (will just have to use wifi overseas).
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