What is MSC (mobile services switching center)

Technical details of the Mobile Services Switching Center (MSC), a crucial component in wireless communication networks. The MSC plays a pivotal role in circuit-switched networks like GSM (Global System for Mobile Communications) and older technologies. Here’s a comprehensive explanation:

1. Architecture:
   • The MSC is part of the Network Switching Subsystem (NSS).
   • It acts as a central control entity, managing call routing, setup, and release procedures.
   • The MSC interacts with other network elements, including:
     • Base Station Subsystems (BSS): Consisting of Base Station Controllers (BSC) and Base Transceiver Stations (BTS), which handle radio communication with mobile devices.
     • Home Location Registers (HLR): Stores subscriber information.
     • Visitor Location Registers (VLR): Provides real-time location information for roaming subscribers.
2. Control Function:
   • The MSC is responsible for:
     • Call Routing: Determining the optimal route for calls based on factors like network load, signal quality, and preferences.
     • Call Setup: Establishing connections between calling and called parties, involving multiple network elements and interfaces.
     • Call Release: Releasing allocated resources (radio channels and network connections) when calls are completed or terminated.
     • Handovers: Managing handovers between different cells as mobile devices move, ensuring call continuity.
3. Connection to BSS:
   • The MSC connects to the BSS, allowing seamless handovers as mobile devices switch cells.
   • It controls the establishment and release of connections to and from the BSS.
4. Call Establishment and Management:
   • Call Setup:
     • When a call is initiated, the MSC determines the location of the called party through interactions with the HLR and VLR.
     • It establishes a connection path involving multiple network elements.
   • Routing:
     • The MSC selects the optimal route for the call, considering various parameters.
     • It communicates with the appropriate BSS to establish a radio link.
   • Handovers:
     • As a mobile device moves, the MSC manages handovers between cells to maintain call continuity.
     • It decides when to initiate a handover and selects the target cell based on signal strength.
   • Call Termination:
     • When the call ends, the MSC releases allocated resources and updates relevant databases.
5. Resource Management:
   • The MSC monitors and manages network resources:
     • Ensures efficient utilization.
     • Optimizes the network for ongoing and future calls.
6. Interfaces:
   • HLR/VLR Interface:
     • Communicates with the HLR to obtain subscriber information.
     • Accesses real-time location information from the VLR for roaming subscribers.
   • Inter-MSC Interface:
     • Facilitates call routing between subscribers served by different MSCs.
7. Security and Authentication:
   • The MSC ensures secure communication by verifying subscriber identities and authorizing access.