The International Mobile station Equipment Identity (IMEI) is composed as shown in
Figure 10.
The IMEI is composed of the following elements (each element shall consist of decimal digits only):
-
Type Allocation Code (TAC). Its length is 8 digits;
-
Serial Number (SNR) is an individual serial number uniquely identifying each equipment within the TAC. Its length is 6 digits;
-
Check Digit (CD) / Spare Digit (SD): If this is the Check Digit see paragraph below; if this digit is Spare Digit it shall be set to zero, when transmitted by the MS.
The IMEI (14 digits) is complemented by a Check Digit (CD). The Check Digit is not part of the digits transmitted when the IMEI is checked, as described below. The Check Digit is intended to avoid manual transmission errors, e.g. when customers register stolen MEs at the operator's customer care desk. The Check Digit is defined according to the Luhn formula, as defined in
Annex B.
The security requirements of the IMEI are defined in
TS 22.016.
The International Mobile station Equipment Identity and Software Version Number (IMEISV) is composed as shown in
Figure 11.
The IMEISV is composed of the following elements (each element shall consist of decimal digits only):
-
Type Allocation Code (TAC). Its length is 8 digits;
-
Serial Number (SNR) is an individual serial number uniquely identifying each equipment within each TAC. Its length is 6 digits;
-
Software Version Number (SVN) identifies the software version number of the mobile equipment. Its length is 2 digits.
Regarding updates of the IMEISV: The security requirements of
TS 22.016 apply only to the TAC and SNR, but not to the SVN part of the IMEISV.