GSM is a 2/2.5 Generation cellular mobile technology prevalent in many parts of the world (with 3G and LTE-4G being deployed in developed countries). GSM has been divided into subsystems into functional categories broadly named as Access Networks and Core Network. Access Network scope includes RF (Radio Frequency) and BSS (Base Station Subsystem) while Core Network includes NSS (Network Switching Subsystem) and IN (Intelligent Network)/VAS (Value Added Services) domains.
Most operators worldwide include management of MSC, MGW (Media Gateway), STP (Signal Transfer Point), HLR (Home Location Register), VLR (Visitor Location Register), SGSN (Serving GPRS Support Node), GGSN (Gateway GPRS Support Node), NMS (Network Management Server), Protocol Analyzer/Signaling Probe etc in the NSS domain while IN/OCS (Online Charging System), iGWB (Charging Gateway), URP (Universal Resource Platform), RBT/CRBT (Calling Ring Back Tone) Servers, SCP (Signaling Control Point) etc are owned by the IN/VAS department.
Major function of Core network is switching of calls, provide connectivity with external networks (other PLMN (OMO - Other Mobile Operators) /PSTN/LDI (Long Distance International) Operators/Internet), Charging of subscribers etc.
Most operators worldwide include management of MSC, MGW (Media Gateway), STP (Signal Transfer Point), HLR (Home Location Register), VLR (Visitor Location Register), SGSN (Serving GPRS Support Node), GGSN (Gateway GPRS Support Node), NMS (Network Management Server), Protocol Analyzer/Signaling Probe etc in the NSS domain while IN/OCS (Online Charging System), iGWB (Charging Gateway), URP (Universal Resource Platform), RBT/CRBT (Calling Ring Back Tone) Servers, SCP (Signaling Control Point) etc are owned by the IN/VAS department.
Major function of Core network is switching of calls, provide connectivity with external networks (other PLMN (OMO - Other Mobile Operators) /PSTN/LDI (Long Distance International) Operators/Internet), Charging of subscribers etc.










