Turns out that such functionality is actually supported natively by the watch. https://support.apple.com/en-us/HT203032 https://support.apple.com/en-us/HT203032

Turns out that such functionality is actually supported natively by the watch. https://support.apple.com/en-us/HT203032 https://support.apple.com/en-us/HT203032 as long as as you have any of these carriers: https://support.apple.com/en-us/HT204039 https://support.apple.com/en-us/HT204039 Though to your point it did take me a bit of ducking to figure this out. Seems extremely straightforward once you know it exists.