IMEI (International Mobile Equipment Identity)

The International Mobile Equipment Identity is a 15-digit number that uniquely identifies a mobile device, independent of the SIM. It encodes the Type Allocation Code (manufacturer and model) and a serial number, and is checked against the EIR to block stolen, cloned, or non-type-approved equipment. Because the IMEI is transmitted to the network during attach, it has been used in tracking attacks and law-enforcement device identification; tamper-resistant IMEI storage and operator EIR hygiene are standard countermeasures.

Categories: Radio Access NetworkIdentity and SubscriberThreats and Attacks

IMEI in context

The radio access network is the layer where mobile devices attach to the operator's infrastructure. Attacks in this layer include IMSI catching, rogue base stations, downgrade attacks and jamming, and defenses hinge on mutual authentication, integrity-protected signaling and Open RAN supply-chain hygiene.

Subscriber identifiers (IMSI, SUPI, MSISDN, IMEI) are the anchor for authentication, charging, lawful interception and fraud analytics. Any protocol or interface that leaks a permanent identifier is treated as a serious privacy defect, which is why 5G introduced SUCI concealment on the air interface.

To place IMEI in the wider telecom-security picture, review Cell Phone (Mobile Phone), CPE, Firmware, IRSF, iSIM and MCC.

Related terms

Equipment

Devices and modems (UE, baseband, IoT, CPE, IMEI)

Articles in the P1 mobile network security guide

Related topic hubs

  • Diameter Attacks S6a IDR/PUR/CLR abuse, subscriber tracking, LTE signaling attacks.
  • NAS Security Non-Access Stratum security, integrity and ciphering algorithms.
  • SIM Swap Attack SIM swap fraud, port-out and account takeover risk.

More from the TelcoSec Glossary

Browse the full TelcoSec Glossary, the Ultimate Guide to Mobile Network Security, or the P1 Arsenal of telecom-security tools.