SylkServer is a SIP application server based on SIP SIMPLE Client SDK that can be programmed to perform SIP end-point applications. Examples of such server applications are conferencing, media offline storage, playing voice prompts, IVR, or gateway to other protocols like XMPP. The server supports SIP signaling over TLS, TCP and UDP transports, RTP and MSRP media planes, has built in capabilities for creating ad-hoc SIP multimedia conferences with HD Audio, IM and File Transfer and can be easily extended with other applications by using Python language.


SylkServer is not designed to transparently route packets, authorization, accounting and handle NAT traversal for signaling or media. Performing applications like SIP Proxy, Registrar, or Presence Agent are out of its scope. SylkServer must be typically deployed behind a SIP Proxy for providing such functions.

For large scale deployments, SylkServer is horizontally scalable with the amount of available hardware by using AG Projects' SIP Thor, a P2P based self-organizing network technology.

Implemented Standards

  • MSRP protocol RFC4975
  • MSRP relay extension RFC4976
  • MSRP File Transfer RFC5547
  • MSRP Alternative Connection Model RFC6135
  • MSRP switch draft-ietf-simple-chat-10
  • Indication of Message Composition RFC3994
  • CPIM Message Format RFC3862
  • Conference event package RFC4575
  • A Framework for Conferencing with SIP RFC4353
  • Conferencing for User Agents RFC4579
  • 5.1 INVITE: Joining a Conference Using the Conference URI - Dial-In
  • 5.2 INVITE: Adding a Participant by the Focus - Dial-Out
  • 5.5 REFER: Requesting a Focus to Add a New Resource to a Conference
  • 5.11 REFER with BYE: Requesting a Focus to Remove a Participant from a Conference

Implemented Standards

The server implements relevant features from the following standards:

SIP-XMPP Gateway specifications (roadmap)