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MSC — Mobile Switching Centre

The MSC is the call‑control heart of the circuit‑switched core. It holds the visitor location register (VLR) for the subscribers currently in its service area, sets up and tears down voice calls, carries SMS, and manages mobility — location updates, paging and handovers — for those subscribers. It reaches the radio side over RAN/BSC connections (A‑interface, driven over M3UA/SS7), bridges voice to the IMS and interconnect through SIP peers, and steers the actual media through one or more media gateways. OmniWeb surfaces the MSC's live subscribers, calls, SMS transactions, RAN and SIP peers, routing table and pending pages; longer‑run trends are on the Grafana dashboards reached from the same page.

← Operations Guide

The MSC is a per‑instance element page reached from the sidebar when one runs in the site's inventory, and — where several are deployed — a fleet view for aggregate status. All traffic goes through the OmniWeb backend proxy to the MSC's API, so it stays behind the single authenticated gateway. The documentation link in the page header (the in‑context help button) opens this page. It is organised into tabs.

Overview​

The MSC overview — API health and a summary of registered subscribers, active calls, SMS transactions, RAN connections and SIP peer status

A single‑screen health read: the API status of the MSC and a summary of what it is currently handling — registered subscribers in the VLR, active calls, in‑flight SMS transactions, live RAN connections and the state of the SIP peers and STP signalling links. It is the quickest way to confirm the MSC is up and see, at a glance, its live load.

Subscribers​

The MSC subscribers tab listing VLR subscribers by IMSI/MSISDN with their registration and location state

Every subscriber the VLR currently holds, each row keyed by IMSI and MSISDN with its registration and location state. Opening a subscriber shows its full VLR context. From here an operator can:

  • Purge a subscriber from the VLR — clear a stale or stuck registration so the subscriber re‑registers cleanly.
  • Run a subscriber action against a specific subscriber.
  • Manage supplementary services — inspect and change the call‑forwarding, barring and related services active for the subscriber.
  • Send Advice of Charge (AoC) to the subscriber.
  • Send a silent SMS (Type 0) or initiate a silent call — a location/reachability probe that does not alert the handset.

Calls​

The MSC calls tab listing active calls with their calling and called parties, state and duration

Every active call, each row showing the calling and called parties, the call state and its duration. Opening a call shows its full detail — the legs, the serving RAN connection and the media path. An operator can force‑release a call to clear a stuck or unwanted call.

SMS​

The MSC SMS tab listing active SMS transactions with their originator, recipient and delivery state

The SMS transactions the MSC is currently handling, each showing the originator, recipient and delivery state, so you can confirm messages are being carried and spot ones that are stuck.

RAN​

The MSC RAN tab listing active RAN connections and the known BSCs learned from RESET exchanges

The radio side of the MSC. It lists the active RAN connections — the live A‑interface associations carrying subscriber signalling — and the known BSCs, learned from the RESET exchanges on the SS7/M3UA links. This is where you confirm the base‑station controllers are connected and see which subscribers are on which connection.

SIP Peers​

The MSC SIP peers tab listing each SIP peer with its address and reachability status

The SIP peers the MSC bridges voice through — the IMS, softswitches and interconnect trunks — each row showing the peer's address and its reachability status. Opening a peer shows its detail. An operator can trigger an OPTIONS ping on a peer to actively test reachability, which is the quickest way to prove a SIP path is up when calls to it are failing.

Media Gateways​

The MSC media gateways tab listing the connected media gateways and their status

The media gateways the MSC steers voice bearers through, each row showing the gateway and its status, so you can confirm the media plane is available for call setup.

Routing​

The MSC routing tab listing the number‑routing rules by prefix and their destinations

The MSC's number‑routing table — the rules that decide, by dialled‑number prefix, where a call is sent. Each rule shows its prefix and destination. An operator can:

  • Add a route — a new prefix and its destination.
  • Remove a route by prefix.
  • Test a route lookup for a number — enter a number and see which route it resolves to, to confirm dialling plans before or after a change.

Paging​

The MSC paging tab listing pending paging requests for subscribers being located

The pending paging requests — the subscribers the MSC is currently trying to locate over the radio network for an incoming call or SMS. An operator can also page a subscriber directly from here.

Logs​

The Logs tab tails the MSC's live log output for troubleshooting a single switch without leaving OmniWeb.

Monitoring dashboards​

Call rates, SMS volumes, subscriber counts and other time‑series for the MSC are presented as Grafana dashboards, reached from the element page — OmniWeb does not duplicate those charts natively.

  • The HSS holds the subscriber data the VLR resolves against and where the MSC registers as the serving node.
  • The CSCF / IMS is bridged over the MSC's SIP peers for voice.
  • The BSCs connect on the radio side over the A‑interface, carried on the SS7/M3UA signalling links.
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