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The Sonus WebRTC Gateway (WRTC) technology enables web browsers to participate in audio, video, and data communications, without any kind of additional plug-ins or application downloads. Using a WRTC enabled browser, user can place a call, participate in multi-party video and audio conferencing, and engage in screen sharing collaboration. Sonus Web Service Solution bridges the web and SIP worlds to facilitate the integration of communications (voice, video, and data) in applications.

The Sonus  is a component of Sonus Web Service Solution. The  provides media service functionality when the WRTC endpoints are behind a NAT.

The  acts as a WRTC to SIP media gateway. It enables WRTC users to communicate to any back-end SIP system and PSTN. The  also provides routing, security, transcoding, and interworking. It supports the following functionalities:

  • Relays and monitors the media streams.

  • Inter-works WRTC media DTLS/SRTP to traditional RTP/UDP.

  • Relays or transcodes opus to G7xx voice codecs.

  • Relays VP8/VP9, and H.264 video codecs.

  • Supports ICE and STUN procedures for NAT traversal.

ICE-Lite Support


The Datagram Transport Layer Security (DTLS) protocol is designed to provide authentication, data integrity, and confidentiality for communications between two applications over an Unreliable Datagram Protocol (UDP). The Secure Real-time Transport Protocol (SRTP) provides encryption, message authentication and integrity, and replay protection to the RTP data in both unicast and multicast applications. DTLS-SRTP is an extension to the DTLS protocol, where DTLS acts as the key management protocol. DTLS protocol is also extended to negotiate the SRTP crypto suites and parameters for use with those keys.

The WRTC is a signaling protocol defined for the real time communication between the Web Browsers. The WRTC has assigned DTLS-SRTP protocol for the media exchange between the browsers. With the implementation of this feature, the  supports:

  • Real time communication between the web browsers by using DTLS-SRTP while inter-working with SIP networks.
  • DTLS on the media path for key management for the SRTP based media.
  • The self-signed certificates to secure and authenticate DTLS associations. DTLS connections are secured by the two browsers sharing self-signed certificates as part of the media connection during a DTLS handshake between the browsers. The certificates are authenticated by checking a fingerprint, which is passed in the signaling path as part of the Session Description Protocol (SDP).

For configuration details, see Configuring SBC for WRTC.