IMEI
The unique number that identifies a mobile phone or cellular device.
Updated
An IMEI is a 15-digit number that identifies a mobile phone or other cellular device. Repair shops record it at check-in so there is no doubt which device was left with them.
For example: a phone repair shop records the IMEI when a phone is booked in, so the device that comes back is provably the one that was dropped off, and a lost or stolen phone can be checked. It is also the number a manufacturer or carrier asks for when checking a warranty or whether a phone is locked to a network.
How Primemgr handles this
Primemgr's device-repair setup records a serial number or IMEI on each device, so a repair is tied to the exact handset.