(NSS) GSM. /ISDN, BSS. NSS , , . NSS , HLR VLR.
() MSC (Mobile Switching Center) ISDN. MSC BSC, MSC, GSM. MSC BSC. MSC (GMSC) /ISDN. MSC , , MSC. 7.
( ) HLR (Home Location Register) , . HLR . ISDN (MSISDN), . HLR , , LAI, MS . , , , .
VLR (Visitor Location Register) , MSC. LAI, VLR, , VLR . , .
GSM OSS .
OMC (Operation and Maintenance Center) GSM (MSC, BSC, GMSC .). , , , . MN (Telecommunication Management Network), ITU-T [21]. network TMN , . GSM NMC (Network Management Center).
AUC(Authentication Centre) , , SIM-. AUC , SIM- , . UC , , .
EIR (Equipment Identity Register) , .
IMEI, ( , .)