To switch a call to a mobile subscriber, the right identities need to be involved. It is therefore important to address them correctly. Followings are those identities;
Mobile Station ISDN Number (MSISDN)
The MSISDN is a number, which uniquely identifies a mobile telephone subscription in the public switched telephone network numbering plan. These are the digits dialed when calling a mobile subscriber.
The MSISDN is consisted with followings;
- Country Code (CC)
- National Destination Code (NDC)
- Subscriber Number (SN)
MSISDN = CC + NDC + SN
International Mobile Subscriber Identity (IMSI)
The IMSI is a unique identity allocated to each subscriber to allow correct identification over the radio path and through the network and is used for all signaling in the PLMN. All network-related subscriber information is connected to the IMSI. The IMSI is stored in the SIM, as well as in the HLR and in the serving VLR.
The IMSI is consisted with followings;
- Mobile Country Code (MCC)
- Mobile Network Code (MNC)
- Mobile Subscriber Identification Number (MSIN )
IMSI = MCC + MNC + MSIN
Temporary Mobile Subscriber Identity (TMSI)
The TMSI is a temporary number used instead of IMSI to identify an MS. The TMSI is used for the subscriber’s confidentiality on the air interface. The TMSI has only local significance (that is, within the MSC/VLR area) and is changed at certain events or time intervals.
International Mobile Equipment Identity (IMEI)
The IMEI is used for equipment identification and uniquely identifies a MS as a piece or assembly of equipment.
The IMEI is consisted with followings;
- Type Approval Code (TAC), determined by a central GSM body
- Final Assembly Code (FAC), identifies the manufacture
- Serial Number (SNR), uniquely identifies all equipment within each TAC & FAC
- Spare, a spare bit for future use.
IMEI = TAC + FAC + SNR + Spare
Mobile Station Roaming Number (MSRN)
A MSRN is used during the call setup phase for mobile terminating calls. Each mobile terminating call enters the GMSC in the PLMN. The call is then re-routed by the GMSC, to the MSC where the called mobile subscriber is located. For this purpose MSRN is allocated by the MSC and provided to the GMSC.
The MSRN is consisted with followings;
- Country Code (CC)
- National Destination Code (NDC)
- Subscriber Number (SN)
MSRN = CC + NDC + SN
Location Area Identity (LAI)
The LAI is used for paging, to indicate to the MSC in which Location Area (LA) the MS is currently situated and also for location updating of mobile subscribers.
The LAI is consisted with followings;
- Mobile Country Code (MCC)
- Mobile Network Code (MNC)
- Location Area Code (LAC)
LAI = MCC + MNC + LAC
Cell Global Identity (CGI)
Each cell is identified by cell identity (CI). A CI is unique within a location area (LA).
CGI is consisted with following;
- Mobile Country Code (MCC)
- Mobile Network Code (MNC)
- Location Area Code (LAC)
- Cell Identity (CI)
CGI = MCC + MNC + LAC + CI
Base Station Identification Code (BSIC)
In GSM, the mobile station uses BSIC to distinguish between neighboring base station.
The BSIC is consisted with
- Network Colour Code (NCC)
- Base Transceiver Colour Code (BCC).
