eSIM

An eSIM (embedded SIM) is a SIM whose subscription is delivered as a downloadable profile rather than on a plastic card. The profile is installed over the air onto a secure chip in the device — the eUICC — which can hold several profiles and switch between them without anyone touching the hardware.

How an eSIM works

A plastic SIM and an eSIM profile carry the same kind of data: an IMSI, authentication keys, network settings and operator applications. The difference is how that data arrives. With an eSIM, the operator prepares an encrypted profile on an SM-DP+ server, and the device downloads and installs it using GSMA Remote SIM Provisioning (RSP).

The download usually starts from an activation code — often scanned as a QR code — or from a discovery service that tells the device a profile is waiting. Each eUICC has a permanent EID, while each installed profile has its own ICCID.

“eSIM” is often used loosely for the chip, the profile or the whole service. Strictly, the chip is the eUICC and the downloadable subscription is the profile.

Consumer vs. IoT eSIM

	Consumer eSIM	IoT eSIM
Specification	SGP.22	SGP.32
Typical devices	Phones, tablets, watches, laptops	Trackers, meters, modules, vehicles
Who starts a download	The user, through the LPA	A remote manager, the eIM
User interface needed	Yes	No

Older machine-to-machine deployments use SGP.02, a server-push model that SGP.32 is designed to replace for new IoT products.

Why it matters for testing

An eSIM adds steps that a physical SIM never had: the profile must be found, downloaded, installed and enabled before the device can even attempt to attach. Each step can fail on its own — a mistyped activation code, a profile already consumed, a certificate mismatch — and a perfectly installed profile can still fail on the network if its roaming agreements do not cover the country where the device is used. Verifying an eSIM product means testing the provisioning path and the network behavior that follows, on real hardware.

SimCheck.ai downloads eSIM profiles onto real cellular modems and then checks registration, data, SMS and voice on live networks. See eSIM testing for details.