Mobile Switching Center

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What Does Mobile Switching Center Mean?

A mobile switching center (MSC) is the centerpiece of a network switching subsystem (NSS). The MSC is mostly associated with communications switching functions, such as call set-up, release, and routing. However, it also performs a host of other duties, including routing SMS messages, conference calls, fax, and service billing as well as interfacing with other networks, such as the public switched telephone network (PSTN).

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The MSC is structured so that base stations connect to it, while it connects to the PSTN. Because cellphones connect to these base stations, all forms of communication, whether between two cell phones or between a cell phone and a landline telephone, travel through the MSC.

Techopedia Explains Mobile Switching Center

A small network operator may employ only one MSC, while a large operator requires multiple MSCs. The MSC plays a significant role in handovers, particularly handovers involving multiple base station controllers – known as inter-BSC or intra-MSC handovers – as well as those involving multiple MSCs, known as inter-MSC handovers.

In an inter-BSC handover and upon detecting that a mobile device is approaching the edge of its cell, a BSC requests handover assistance from its MSC. The MSC then scans a list of adjacent cells and their corresponding BSCs and facilitates the handover to the appropriate BSC.

As mobile phones move, it is important for the MSC to determine each phone’s location to effectively facilitate routing communications between them. For this task, the MSC works with a large database known as the home location register (HLR), which stores relevant location and other information for each mobile phone.

Because accessing the HLR uses many network resources, most operators employ visitor location registers (VLRs). These are relatively smaller databases, which are integrated with the MSC. Some carriers deploy one VLR per MSC, while others set up one VLR to serve multiple MSCs.

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Margaret Rouse
Senior Editor
Margaret Rouse
Senior Editor

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.