An eSIM can dramatically alter how you use your smartphone. Unlike removable subscriber identity module (SIM) cards, eSIMs are a permanent part of your phone and enable you to use two different numbers on the same device. You can use an eSIM to add cellular connectivity to tablets, smartwatches, and other devices as well.
Don't feel bad if you've never heard of eSIMs. The nascent technology has been in the works for over a decade but only became available to the general public a few years ago. It’s possible that Steve Jobs wanted the first iPhone to jettison physical card slots, and rumors persist that Apple could be launching an eSIM-only device in the near future.
Quick lingo note: The phrase “physical SIM” often refers to the older card that you pop out the side of your phone. While an eSIM is much smaller, it is not immaterial. The wording “removable SIM” makes more sense in contrast and emphasizes the embedded quality of eSIMs.
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