A UIMID (user identity module identifier) is a 32-bit

Electronic Serial Number Electronic serial numbers (ESNs) were created by the U.S. Federal Communications Commission (FCC) to uniquely identify mobile devices, from the days of Advanced Mobile Phone System, AMPS in the United States starting in the early 1980s. The adminis ...

(ESN) stored in a

R-UIM Removable User Identity Module (R-UIM, usually pronounced as "R-yuim") is a card developed for cdmaOne/CDMA2000 ("CDMA") handsets that extends the GSM SIM card to CDMA phones and networks. To work in CDMA networks, the R-UIM contains an early ve ...

or CSIM ('smart card') used for TDMA or

CDMA2000 CDMA2000 (also known as C2K or IMT Multi‑Carrier (IMT‑MC)) is a family of 3G mobile technology standards for sending voice, data, and signaling data between mobile phones and cell sites. It is developed by 3GPP2 as a backwards-compatib ...

phones (mainly the latter). It is given a different name to avoid confusion with the hardware ESN stored in the phone. In all known systems the UIMID displaces the ESN in signaling (based on setting bit 1 of the 'UsgInd' field to '1' in the card). Because the UIMID is allocated from the same numbering space as ESN its existence is transparent to the network. The reason the UIMID is transmitted instead of the ESN is because the card contains the MIN or IMSI and devices such as the HLR running the Asbi mobility management protocol insist on a static association between these identifiers for subscription validation. The HLR will store the MIN or IMSI alongside the ESN in each record, and if an ANSI-41 message is received containing a different pair it will be rejected as invalid. UIMID codes are allocated by the TIA using industry-defined guidelines and with codes that have been transferred from the ESN administrator (also the TIA).3GPP2 SC.R4004-0, Version 2.0. May, 2010
User Identification Module ID Manufacturer’s Code Assignment Guidelines and Procedures
/ref> ESN and UIMID codes were exhausted by late 2008 at which point only reclaimed codes could be assigned to manufacturers including portions of blocks assigned to manufacturers but never used and portions used for technologies other than

. The TIA stopped accepting applications for UIMID blocks on June 30, 2010. Only one assignment has been made since 2010. The replacement identifier for UIMID is

EUIMID EUIMID (expanded UIMID) is a unique identifier for an R-UIM (Removable User Identity Module) or CSIM (CDMA SIM application) card in CDMA2000 cellular systems that replaces the older UIMID identifier. There are two forms of EUIMID, known as Short ...

although for backwards compatibility a pseudo-UIMID (pUIMID) is still retained in cards. The pUIMID is composed of the prefix 0x80 to make it distinct from unique UIMID codes and a 24-bit SHA-1 hash of the EUIMID. pUIMID codes are not unique as there are only 2²⁴ of them and many times more EUIMID codes. The pUIMID can usually be used in place of a unique UIMID, except when uniqueness is important.

References

External links

Official TIA Resource Page for ESN and UIMID

CDMA Development Group MEID and EUIMID resource page
Mobile technology Wireless Identification {{Wireless-stub