The EID (eUICC Identifier) is the serial number of the reprogrammable eSIM chip soldered into your phone, tablet or watch. It is a 32-digit decimal number, unique to that one device, and it exists only on hardware that actually supports eSIM. That is why it doubles as the simplest proof of eSIM capability: if your device shows an EID, it can run a travel eSIM.
The fastest way to find it is to dial *#06# on the keypad. On an eSIM-capable phone this opens a panel showing both the IMEI and, below it, the EID; on an older device with no eSIM, no EID appears. You can also read it in settings, usually under the mobile or cellular section near the eSIM options.
People often search for an “EID number for eSIM” when a provider asks for it during activation, though most travel eSIMs install by QR code and never request it. Where it earns its keep is diagnosis: support can use the EID to confirm your device genuinely has an eSIM before issuing an eSIM profile.
Do not confuse the EID with the IMEI. The IMEI identifies the whole device to the network, while the EID identifies only the embedded eSIM chip. To check whether your exact model qualifies, use our device compatibility page or read how to check eSIM compatibility before you buy.