GSM Architecture and Definitions (2)

    The Network Switching System  
 
The Network switching system (NSS) is responsible for performing call processing and subscriber-related functions. The switching system includes the following functional units.

GSM Architecture and Definitions

MSC: Mobile Switching Center a switching exchange whose main functions are:
       – Call Handling
       – Specific GSM functions such as:
         • Mobility Management: Communication with the Location Databases (VLR
           and HLR)
         • Handover execution when involved
       – Gateway Function for Terminating Call (TC)
    VLR: Visitor Location Register is associated with one or more MSC. It is a local database with the following
         information:
         – Copy of the HLR data for visiting subscribers
         – More precise location of the Mobile Station (an area of the network called
           “Location Area” which is a group of cells
         – Call re-direction data

GSM Architecture and Definitions

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