A state of the art, extensible SIP Application Server
Zero-configuration multi-party conferencing

Description

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.

Deployment

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.

SylkServer is horizontally scalable with the amount of available hardware by using SIP Thor, a P2P based self-organizing network technology.

Features

SIP Signaling

TLS, TCP and UDP transports
INVITE, MESSAGE, REFER
SUBSCRIBE, NOTIFY
XMPP Gateway

Conferencing

Conference participants
Wideband RTP mixer
MSRP switch
XMPP MUC

NAT Traversal

SIP Outbound Proxy
ICE clients
MSRP Relay clients
MSRP ACM clients

Voice over IP

Wideband (G722 and Speex)
Narrowband (G711 and GSM)
sRTP encryption
Hold/Unhold

Instant Messaging

MSRP and XCAP protocols
CPIM envelope
Is-composing indicator
Delivery reports

File Transfer

MSRP protocol
Progress reports
Conference-info extension
Conference room persistent

Implemented Standards

The server implements relevant features from the following standards:

SIP (RFC3261) and related RFCs for DNS, ICE and RTP
MSRP protocol RFC4975
MSRP relay extension RFC4976
MSRP File Transfer RFC5547
MSRP switch draft-ietf-simple-chat-18
MSRP Alternative Connection Model RFC6135
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
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
XMPP core (RFC 6120) http://xmpp.org/rfcs/rfc6120.html
XMPP extensions http://xmpp.org/xmpp-protocols/xmpp-extensions
Instant Messaging and Presence http://xmpp.org/rfcs/rfc6121.html
Interworking between the Session Initiation Protocol (SIP) and the Extensible Messaging and Presence Protocol (XMPP): http://xmpp.org/internet-drafts/draft-saintandre-sip-xmpp-presence-02.html
Interworking between the Session Initiation Protocol (SIP) and the Extensible Messaging and Presence Protocol (XMPP): http://xmpp.org/internet-drafts/draft-saintandre-sip-xmpp-im-01.html
Interworking between the Session Initiation Protocol (SIP) and the Extensible Messaging and Presence Protocol (XMPP): http://xmpp.org/internet-drafts/draft-saintandre-sip-xmpp-chat-03.html
Jingle XEP-0166
Jingle RTP Sessions XEP-0167
Jingle ICE-UDP Transport Method XEP-0176