VMSC (Visited Mobile Switching Center)

What is VMSC (Visited Mobile Switching Center)?

The Mobile Switching Center (MSC) serving a mobile in the VPLMN (Visited Public Land Mobile Network) is referred to as the Visited Mobile Switching Center.

How does VMSC work?

An MSC serves as the network switching subsystem's (NSS) command center. By switching the digital voice packets between network channels, the MSC connects calls between subscribers.

The MSC is located between the base station and the Public Switched Telephone Network (PTSN). The MSC is used to route all mobile communications from the base station. The MSC is in charge of managing voice calls, SMS, and additional services like FAX. The MSC is in charge of real-time pre-paid billing, account management, and call setup between subscribers.

What are the functions of mobile switching center?

The MSC serves as the main node in a GSM network. It is the node that regulates calls to and from MS's. An MSC's key functions consist of the following:

• Switching & call routing
  To effectively establish a call, an MSC may interact with other nodes and control call setup, supervision, and release. This also applies to calls that are forwarded from MSs to other networks, such the PSTN.

• Direct access to the Internet
  Traditionally, an MSC used established networks, such the PSTN, to connect to an ISP's Internet nodes. However, this feature allows an MSC to communicate with Internet nodes directly, which speeds up call setup. Tigris is an access server that can be used to allow direct access.

• Charging
  An MSC includes features for billing mobile calls as well as details on the specific charge rates to apply to a call at any given time or for a certain destination. This information is captured during a call and is stored afterwards to be sent to a billing center.

• Communication with HLR
  The main time that an MSC and HLR interact is when an MS call is being set up and the HLR is asking the MSC for certain routing data.

• Communication with other MSC’s
  During call setup or handovers between cells belonging to various MSCs, two MSCs may need to communicate with one another.