What is MSC (Mobile Switching Center)

Technical details of the Mobile Switching Center (MSC):

1. Definition and Role:
   • The MSC is a central component within a cellular network, specifically in the context of GSM (Global System for Mobile Communications) and CDMA (Code Division Multiple Access) systems.
   • It serves as the core control center for managing and routing voice and data traffic between various devices within the network, including cellphones, landlines, and other communication endpoints.
   • The primary responsibilities of the MSC include:
     • Call Setup and Release: Initiating and terminating voice calls.
     • Call Routing: Determining the appropriate path for call transmission.
     • SMS (Short Message Service) Routing: Handling text messages.
     • Conference Calls: Managing multi-party calls.
     • Billing and Charging: Tracking usage for billing purposes.
     • Interfacing with External Networks: Connecting to the public switched telephone network (PSTN) and other networks.
2. Network Switching Subsystem (NSS):
   • The MSC is a crucial part of the NSS, which encompasses various elements involved in call switching and management.
   • Other components of the NSS include the Home Location Register (HLR), Visitor Location Register (VLR), and Authentication Center (AuC).
3. Call Routing and Handovers:
   • As mobile phones move within the network, the MSC plays a vital role in ensuring seamless communication.
   • Intra-MSC Handovers: When a mobile device approaches the edge of its cell, the MSC performs handovers to adjacent cells within the same MSC.
   • Inter-MSC Handovers: Involves handovers between different MSCs. The MSC scans adjacent cells and facilitates handover to the appropriate MSC.
   • The MSC relies on the HLR to determine each phone’s location for effective call routing.
   • To minimize resource usage, operators often deploy VLRs integrated with the MSC.
4. Database Interaction:
   • The HLR stores essential information about each mobile phone, including location, subscriber details, and services.
   • The MSC interacts with the HLR to retrieve relevant data during call setup and routing.
5. Multiple MSCs:
   • Large network operators require multiple MSCs to handle the network load efficiently.
   • Each MSC manages a set of base stations (BTS/BSCs) and their associated cells.
   • Inter-MSC handovers involve coordination between different MSCs.