Yup. They call it an eSIM: https://techcrunch.com/2017/09/12/the-cellular-enabled-apple-watch-has-the-sim-built-in/ https://techcrunch.com/2017/09/12/the-cellul

Yup. They call it an eSIM: https://techcrunch.com/2017/09/12/the-cellular-enabled-apple-watch-has-the-sim-built-in/ https://techcrunch.com/2017/09/12/the-cellular-enabled-apple... "The eSIM has to be provisioned via the device itself, which is handy if you want to switch between T-Mobile and AT&T in a hurry, but not handy if you want to switch to a carrier not supported by Apple, or sell your device to someone on a different carrier."