What Is an IMEI Number?

An IMEI (International Mobile Equipment Identity) is a unique 15-digit number that identifies an individual mobile phone or other cellular device. Where a MAC address identifies a device’s network interface on a local network, the IMEI identifies the handset itself to mobile networks - and because it survives factory resets, SIM swaps, and changes of owner, it is one of the most reliable identifiers you can put in a device’s asset record.

What the 15 digits mean

An IMEI breaks into three parts. The first eight digits are the Type Allocation Code (TAC), which identifies the make and model - every unit of the same model starts with the same TAC. The next six digits are a serial portion unique to that individual device. The final digit is a check digit calculated from the others, there to catch typing mistakes.

Two details catch people out. Dual-SIM phones carry two IMEIs, one per SIM slot, on the same physical handset. And IMEIs are not limited to phones: cellular tablets, laptops with mobile broadband, 4G/5G routers, and connected equipment with a SIM all have one. Wi-Fi-only devices do not.

How to find an IMEI number

• *Dial #06# - the IMEI (or both, on dual-SIM devices) appears on screen. Works on nearly every handset, even when locked out of the settings.
• Settings - About phone on Android; General, then About on iOS.
• On the hardware - etched on the SIM tray of many modern phones, or under the back cover of older ones.
• On the original box - printed as a barcode label, useful when the device itself is missing.

IMEI vs serial number

A phone has both, and they do different jobs. The manufacturer’s serial number identifies the device to the maker - it is the reference for warranty claims and support cases. The IMEI identifies the cellular radio to mobile networks, which is why theft reports run on IMEIs: in many countries, carriers can blacklist a reported IMEI so the handset cannot register on a network, stripping most of its resale value.

One consequence worth writing into your process: a warranty replacement is a different physical device with a new IMEI and a new serial. If the record is not updated at the swap, every later lookup points at hardware you no longer own.

Why IMEIs belong in asset records

For a fleet of company phones, the IMEI is what separates two hundred identical black handsets. It is the number the police report, the insurance claim, and the carrier blacklist request all need - hunting for it after the phone is gone means digging through old boxes and invoices. It also settles offboarding disputes: when a leaver hands back “their” phone, the IMEI confirms it is the issued device and not a personal lookalike. In a register like AMPthilly, the IMEI sits in a custom field on the asset record, next to the serial number and a printable QR asset label, so a phone-camera scan at handover pulls up the right device with its owner and history.

Common mistakes

• Recording the box, not the device. If units get shuffled during a rollout, the IMEI on file must come from the handset that was actually issued.
• Capturing only one IMEI on dual-SIM phones. A blacklist request may need both.
• Not updating after a warranty swap. The replacement has new identifiers; the record should too.
• Printing the IMEI on the visible label. The outside of the device should carry your own asset ID as part of normal asset marking - the IMEI lives in the record, not on display.

Related terms

• MAC Address - the hardware identifier for a network interface, recorded alongside the IMEI on connected devices
• Asset Marking - applying durable identifiers to equipment so it can be traced
• QR Code - the scannable label format that links a device to its asset record
• Barcode - the 1D format IMEIs are printed in on device boxes
• Asset Label - the physical label carrying your organisation’s own asset ID