EID

The EID (eUICC Identifier) is a 32-digit number that permanently and uniquely identifies an eUICC — the secure chip inside an eSIM device. It identifies the hardware, not a subscription: the EID stays the same no matter which operator profiles are downloaded, enabled or deleted.

EID structure

Every EID is 32 decimal digits, the last two of which are check digits. Two numbering schemes are in use: the original one from SGP.02, summarized in a GSMA application note, and the newer GSMA-administered scheme in SGP.29:

Scheme	Starts with	Layout
Legacy, based on ITU-T E.118	89	89 + 3-digit country code + 3-digit issuer identifier + 5 digits of platform/OS version + 17 issuer-assigned digits + 2 check digits
GSMA-assigned (SGP.29)	Anything except 89	EUM Identification Number (variable length) + EUM-specific number (the remaining digits) + 2 check digits

The check digits use a modulo-97 calculation over all 32 digits. To validate an EID, treat it as one integer: if the remainder after dividing by 97 is 1, the check digits are correct. This catches most transcription errors before a bad EID reaches a provisioning system.

How the EID is used

• Profile ordering: an operator can bind a profile to one EID on the SM-DP+, so only that chip can download it.
• Discovery: an SM-DS stores pending download events keyed by EID.
• IoT fleet management: in SGP.32, the eIM addresses each device’s eUICC by EID.
• Support and inventory: the EID is printed on device labels or packaging and can be read through device settings or modem commands.

EID vs. ICCID vs. IMSI

The EID identifies the chip. The ICCID identifies one installed profile, and the IMSI identifies the subscriber to the mobile network. An eUICC holding three profiles has one EID, three ICCIDs and at least three IMSIs.

Why it matters for testing

Many provisioning failures trace back to the EID: a profile bound to a different chip, an EID mistyped in an order, or an eUICC whose certificates the SM-DP+ does not accept. Recording which chip each download attempt ran on makes those failures traceable. SimCheck.ai records the site and modem every eSIM profile is installed on, so a failed download can be tied to specific hardware — see eSIM profile download errors.