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The SIP protocol defines several functional components. These functional entities can be implemented as a separate server, or the same server can perform multiple functions. VoipSwitch’s class 5 softswitch acts as:

  • Proxy server — performs call routing, authentication, authorization and address resolution
  • Registrar server — User Agents register their location with a registrar server, which places that information into a location database. A registrar server responds to location requests from other servers.
  • Location server — This server maintains the location database for registered User Agents.
  • Back-to-back user agent (B2BUA) — This server acts as a User Agent server and client at the same time. It terminates the signaling from the calling client and then initiates signaling to the called party. B2BUAs are allowed to change the content of requests, giving them more control over the call parameters.
  • Presence server — This server gathers presence information from Presentities and subscription information from Watchers, and sends status notifications.

VoipSwitch performs its charging and authentication functions through its own, integrated billing module.

VoipSwitch can also interact with other application servers which comprise Voip Box and Media Relay (TURN). They fulfill various roles depending on their configuration and can provide services, such as:

  • Media Gateway – provides services for Calling Cards and Unified Communication features; it is responsible for playing audio from files, playing numbers, providing Voice mail. Also Records conversations to a file or live streaming format.
  • Legal Interception – its role is to stream media with auxiliary session descriptions about the call being intercepted. Required by law in some countries.
  • Transcoding – enables communication for audio stream encoded using different compression methods.
  • TURN Media Relay – provides RTP proxy, part of the ICE call setup scenario.
  • Fax server – encodes documents to the t38 fax protocol so they can be sent over VoIP networks; also decodes and puts in users’ fax boxes (email to fax/fax to email)


Main Features

  • Networking:
    • SIP, IMS extensions
    • Media Relay/Proxy with NAT endpoints handling
    • ICE mechanism for Peer to Peer session establishment, STUN and TURN served by VoipSwitch server
    • SIP SIMPLE Instant Messaging, SIP CPIM
    • Presence Resource List support with Watcher Info
    • XCAP for XDM server (part of Voipswitch platform)
  • Billing:
    • Credit control application, support for Prepaid and Postpaid model
    • Subscriptions, Packages and other service bundling features
    • Charging functions
    • Real time multi layer charging with credit control for each ownership level (Resellers)
  • Routing:
    • Least Cost Routing
    • Load balancing/sharing for termination endpoints
    • Traffic failover with multiple “waterfall” levels
    • Multiple routing plans – partitioning, hosted enterprise SBC, hosted ET platforms
  • Authentication/Authorization:
    • Multilayered accounts ownership structure (Owner, 3 levels of Resellers, Sales Agents)
    • Support for multiple SIP URIs (aliases) per account
    • Support for SIP multidomain environment on the same platform
    • Sharing accounts among services e.g. RCS mobile client shares account with Calling card PIN or PINless service
  • Telephony features/ Enterprise Telephony (PBX):
    • Follow me/Find me
    • Hunt Groups
    • Parking, Queing
    • Call center applications
    • Basic telephony features (transfers, hold, second line, shared line, BLF etc.)
    • Voicemails
    • PBX specific features: Dial by Name, extensions etc.
    • Autoattendants
  • Media Gateway (Voip Box):
    • Playing audio/video – Interactive Voice Response system with xml based flow scenarios
    • Call recording to a file or live stream (mp3, mp4, HLS)
    • Legal Interception
    • Transcoding
  • TURN, Media Relay server:
    • Media Proxy element in ICE mechanism
  • IM/Presence:
    • Subscribe/Publish
    • Watcher Info
    • Resource Lists with XDM
    • XCAP protocol for managing Resource Lists
  • Fax server:
    • T38 protocol
    • Email to fax/fax to email

System capacity and requirements

Cluster configuration

In a cluster comprising 3 to 5 servers the platform is capable of handling on average 10 000 concurrent calls which in effect amounts to double this as this number of sessions include communication from clients to the switch and from the switch to the destination party (client or TDM gateway or application server). All servers can utilize the same accounting, routing and location database. Incoming sessions are routed to the appropriate serving call function proxy. Requests from clients can be distributed among several servers using various technologies. Depending on the configuration, VoipSwitch can act as a media relay or have the media path established directly between peers. Switching media packets requires both computer resources and also a high performance network card.

Single server

VoipSwitch can also run in a single server scenario as it is a fully standalone solution. Only MySQL server should be installed on a separate machine.

High Availability

VoipSwitch supports failover/redundancy scenarios. Contact our technical support to learn more. In addition we offer data and system snapshot backup services.


  • Operating system: Windows 2008 server or Windows 2012 server
  • Database server: MySQL InnoDB or Cluster

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