Features

SIP SIMPLE client SDK is a Software Development Kit for development of Real Time Applications based on SIP and related protocols for Audio, Instant Messaging, File Transfers, Desktop Sharing and Presence. Other media types can be easily added by using an extensible high-level API.

The library has cross platform capabilities on Linux OS, Mac OSX (Leopard and Snow Leopard) and Microsoft Windows (roadmap). The library should work with minimal changes on any platform that supports C and Python development environments. The SIP and media stacks are based on pjsip 1.0 version with relevant patches from later versions applied.

To see SIP SIMPLE client SDK features in action you can try  Blink.

General Features

  • Written in Python Programming Language
  • Non-blocking Asynchronous Engine
  • High Level Middleware
  • Configuration Framework
  • TLS Security for signaling (SIP) and media (MSRP, XCAP)
  • Multiple SIP Accounts support
  • Multiple Media Types per Session (e.g. Audio + IM)
  • Trace capability for all underlying protocols
  • Failover for DNS lookups, SIP and MSRP routing
  • Supports re-INVITE for adding and removing media
  • Automatically handling if IP Address changes
  • Audio Conference Bridge
  • Wav Player and Recorder
  • Acoustic Echo Cancelation (based on Speex MDF algorithm)
  • Answering Machine
  • Wide-band Internet codecs: Speex and G722
  • PSTN compatible codecs: G711, iLBC, GSM

Supported media types:

  • Audio (RTP/sRTP)
  • Instant Messaging (MSRP)
  • File Transfer (MSRP)
  • Desktop Sharing (VNC over MSRP)

All media types can be combined together in the same SIP session.

The library uses a separated from the core lookup mechanism for the next hop routing. This important feature allows the library to be used for building SIP clients that operate in combination with any SIP provider (by employing RFC 3263 DNS lookups), in a server-less LAN operation (using Bonjour protocol) or integrated into a network overlay developed by a third party (e.g. P2PSIP overlay).

Implemented Standards

SIP Signaling

  • SIP, Session Initiation Protocol  RFC3261
  • SDP, Session Description Protocol  RFC4566
  • An Offer/Answer Model with Session Description Protocol (SDP)  RFC3264
  • Reliability of Provisional Responses in Session Initiation Protocol  RFC3262
  • HTTP Authentication: Basic and Digest Access Authentication  RFC2617
  • The Reason Header Field for the Session Initiation Protocol  RFC3326

Address Resolution

NAT Traversal

  • SIP Signaling: Symmetric Response Routing Symmetric media  RFC3581
  • STUN: Session Traversal Utilities for NAT  RFC3489
  • RTP media (Audio and Video): ICE, Interactive Connectivity Establishment  RFC5245
  • MSRP media (Instant Messaging and File Transfer): MSRP protocol relay extension  RFC4976

Voice over IP

  • RTP, A Transport Protocol for Real-Time Applications  RFC3550
  • Real Time Control Protocol (RTCP) attribute in Session Description Protocol (SDP)  RFC3605
  • The Secure Real-time Transport Protocol (SRTP)  RFC3711
  • Generation and parsing of RFC 2833/telephone-events payload in both RTP and SDP  RFC2833

Instant Messaging

Desktop Sharing

Conferencing

  • Conference Event Package  RFC4575
  • A Framework for Conferencing with the Session Initiation Protocol  RFC4353 (work in progress)
  • SIP Call Control - Conferencing for User Agents  RFC4579 (work in progress)
  • MSRP ad-hoc multi-party chat sessions  draft-ietf-simple-chat-06 (work in progress)

Presence

All features have been tested against with  OpenSIPS Presence Agent and  OpenXCAP server.