Glossary
eSIM
An eSIM (embedded SIM, or eUICC) is a SIM chip built into a device that can download and store mobile operator profiles over the air using the GSMA's remote SIM provisioning standard, replacing the need to insert a physical SIM card.
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How it works
The eSIM chip (the eUICC) is soldered into the phone, tablet or watch. Instead of a plastic card, the operator issues a profile — the same credentials a physical SIM holds, including the IMSI and keys. You install it by scanning a QR code or through the operator's app, which contacts the operator's provisioning server (SM-DP+) under the GSMA Remote SIM Provisioning specification.
Most eSIM devices can store several profiles and use one or two at a time, depending on the model. Deleting a profile usually means asking the operator for a new one to reinstall it.
Advantages and limits
Advantages: no physical swapping, faster activation, dual-SIM on phones with one card slot, and easy travel data plans.
Limits:
- The device must support eSIM and, often, be carrier-unlocked.
- Many travel eSIMs are data-only and come with no phone number, so they cannot receive SMS verification codes.
- A phone-number eSIM is still an operator subscription, with that operator's identity checks and billing.
- Moving to a new phone requires a transfer or reissue, which is also the step abused in SIM swap fraud.
eSIM vs a second number
An eSIM is a delivery method for a mobile subscription, not a number type: a number on an eSIM is the same kind of MSISDN as one on a plastic card. If you only need a second line for SMS codes and calls, alternatives include a second SIM or a service such as PhoneBorn, which provides real mobile numbers used from a browser dashboard — no eSIM-compatible phone, SIM slot or ID documents required. See eSIM vs second number vs PhoneBorn and phone number without a SIM for a side-by-side comparison. Travellers who want to keep 2FA working abroad can also read this guide.