Class 4 Softswitch – The Media Gateway for Service Providers

Connecting IP Networks to Public Switched Networks

Sipwise Class 4 Softswitch (C4) was developed in close cooperation with Dialogic.

What the Sipwise Class 4 Softswitch can do

Together with Sipwise Class 5 Softswitch, service providers can offer full integrated telecommunication infrastructures. The C4 enables interoperability between IP and PSTN networks via high-density optical telephony and ethernet connections in one compact 1U form.

The Class 4 Softswitch also transforms media and signalling to support a more efficient and reliable fax, voice and multimedia sessions in mobile and cloud-based applications. It secures these sessions across IP and mixed network boundaries in support of service level agreements.

The softswitch also serves as a support for SS7, SIP signalling, IPv6 and IPv4 interworking along with voice transcoding provides a cost-effective platform to help service providers evolve from a TDM to an all-IP environment.

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C4 Features

  • Scripting Capabilities

    Sipwise C4 features the Dialogic® Programmable Protocol Language (PPL), which allows rapid implementation of SS7 ISUP variants and other signaling changes.

  • Scalability

    Sipwise C4 is scalable from 50 to 2.250 simultaneous SIP sessions with multimedia transcoding, and 128 to 2016 channels of SS7 signaling. The scalable IP and TDM connectivity solution provides high performance on a small scale to help lower OPEX and CAPEX.

  • Routing Features

    • Call routing and translation based on ANI, DNIS, Generic Number (only translation is supported), Nature of Address (NOA)
    • Algorithms include percentage-based routing and disposition by Cause Code
    • Pre- and post-routing digit translations with wildcard support
    • Multiple routing algorithms per trunk group or groups of trunks for IP-to-TDM and IP-to-IP and both A-law and µ-law conversions
    • Pre-call announcement (branding)
  • Transcoding

    Integrated encryption and transcoding support for voice, video, tone and faxing eliminates the need to add separate hardware for supporting both security and transcoding requirements, helping to reduce the number of deployed network elements.

  • IP Bearer Features

    • Coder support: AMR-NB, AMR-WB, G.711, G.723.1, G.729 A/B, G.726, G.722, GSM-FR, GSM-EFR, iLBC, RFC 4040 Clear Channel
    • Video support: Transcoding, transrating, and pass-through of CIF/QCIF resolutions for H.263, H.264, and MPEG-4
    • Echo cancellation: G.168 128 ms tail length
    • Voice activity detection and packet loss concealment
    • Comfort noise generation
    • T.38 real-time fax, T.38 – G.711 interworking
    • Fax/modem bypass
    • Digit transmission via RFC 2833 (SIP)
    • G.711 tones, SIP INFO, RFC 2833 interworking
    • Secure RTP (SRTP) to RTP interworking (SIP audio media only


The Integrated Media Gateway not only provides scalability within a small footprint, but also handles signaling and media in a single carrier-grade chassis and is able to deliver SIP services into SS7, SIGTRAN, PRI, and SIP-I networks. It also manages sessions through capabilities that include SIP mediation, SIP-to-H.323 interworking, SIP back-to-back user agent (B2BUA), and IP-to-IP transcoding of voice and video for network access applications.

With its high density and versatility, Sipwise C4 can help wireless and wireline service providers add new Value-Added Services (VAS) quickly, and provide a clear migration path to an all-IP network. It is also an excellent option for retail, wholesale, and enhanced service VoIP deployments, as well as contact centers and mobile VAS. Its NEBS-3 carrier-ready design uses independent network interfaces to separate transport, signaling and OAM&P for reliability and enhanced service availability.

High Availability

Fast maintenance, such as hot-swappable power supplies, field-replaceable motherboard trays as well as graceful upgrades address the flexibility and ease of operation that carriers need. In addition it increases reliability in the field.

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Fact Sheet

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