Introduction:
The UE identity is very important for authenticating the subscriber to access the network. authentication of subscriber is happened in various procedure via RRC signalings. But to keep the subscriber safe, network allocated some unique identification, which are used to identify the UE at various nodes.
- The 'home' Public Land Mobile Network (PLMN) is identified using a combination of the Mobile Country Code (MCC) and Mobile Network Code (MNC). The ITU is responsible for allocating the MCC, whereas the national administrator is responsible for allocating the MNC. A UE uses the 'home' PLMN Identity when searching for a network, e.g. when completing a band scan, a UE will search for a cell which is broadcasting the 'home' PLMN Identity within SIB 1.
- The subscriber is identified within the home PLMN using the Mobile Subscriber Identification Number (MSIN).
- MSIN is allocated by the service provider.
- The Type Allocation Code (TAC) is an 8 digit number which identifies the UE model. It can also identify a specific version of a UE model, i.e. different versions of the same UE model can be allocated different TAC. The TAC is allocated by the GSM Association (GSMA).
- The Serial Number (SNR) uniquely identifies a device with a specific TAC. All UE which have the same TAC should be allocated different Serial Numbers. The Serial Number is allocated by the device manufacturer.
- The Check Digit (CD) is calculated from a combination of the TAC and Serial Number. It provides a mechanism for detecting data entry errors, e.g. when the IMEI is manually entered into a system.