主頁（http://www.by236.com）：PJSIP開源SIP協議棧

PJSIP 開源SIP協議棧是英國公司Teluu Ltd維護的SIP開源項目。

官方是這樣描述PJSIP協議棧的：

PJSIP是免費開源的多媒體通信的軟件包，支持的協議包括：SIP, SDP， RTP, STUN, TURN, 和ICE。它提供了基于SIP的多媒體開發框架，和NAT 支持包，通過高級API 接口提供支持。因此，它可以支持桌面系統開發，嵌入式開發和移動手持設備的開發。

PJSIP本身非常緊湊，功能非常豐富。支持語音，視頻，在線狀態，及時通訊服務，具有非常詳細的開發文檔。PJSIP本身具有非常良好的可移植性，支持多種操作系統和開發環境，例如windows, Linux, Mac和安卓操作系統。

2005年，PJSIP 由一個小的開發團隊發起。經過多年的持續開發和維護，目前來自世界各地的上百個開發人員參與了這個項目。從2007開始，一直配合SIPit 進行SIP兼容性測試。

PJSIP 數據手冊

支持的操作系統

• Mac OS X
• Windows (32 and 64bit), including Windows 8
• Linux/uClinux
• Smartphones:
  • iPhone OS/iOS including iOS 7 (on iPhone, iPad, iPod Touch) with iOS background support
  • Android
  • BlackBerry (BB10)
  • Windows Mobile/Windows CE
  • (Windows Phone 8 is currently under development)
  • Symbian S60 3rd Edition and 5th Edition
• Community supported:
  • OpenBSD
  • FreeBSD
  • Solaris
  • MinGW
  • RTEMS

SIP 處理能力

• Base specs:
  • Core methods: RFC 3261: INVITE, CANCEL, BYE, REGISTER, OPTIONS, INFO
  • Digest authentication (RFC 2617)
• Transports:
  • UDP, TCP, TLS (server or mutual)
  • DNS SRV resolution (RFC 3263)
  • IPv6 (UDP only)
  • QoS (DSCP, WMM)
• Routing/NAT:
  • rport (RFC 3581)
  • Service-Route header (RFC 3608)
  • SIP outbound for TCP/TLS (RFC 5626)
  • Path header (with SIP outbound) (RFC 3327)
• Call:
  • Offer/answer (RFC 3264)
  • hold, unhold
  • redirection
  • transfer/REFER (attended and unattended):
    • Base (RFC 3515)
    • replaces (RFC 3891)
    • Referred-by (RFC 3892)
  • sipfrag support (RFC 3420)
  • norefersub (RFC 4488)
  • UPDATE (RFC 3311)
  • 100rel/PRACK (RFC 3262)
  • tel: URI (RFC 3966)
  • Session Timers (RFC 4028)
  • Reason header (RFC 3326, partially supported)
  • P-Header (RFC 3325, partially supported)
• SDP:
  • RFC 2327 (obsoleted by RFC 4566)
  • RTCP attribute (RFC 3605)
  • IPv6 support (RFC 3266)
• Multipart (RFC 2046, RFC 5621)
• Presence and IM:
  • Event framework (SUBSCRIBE, NOTIFY) (RFC 3265)
  • Event publication (PUBLISH) (RFC 3903)
  • MESSAGE (RFC 3428)
  • typing indication (RFC 3994)
  • pidf+xml (RFC 3856, RFC 3863)
  • xpidf+xml
  • RPID (subset) (RFC 4480)
• Other extensions:
  • INFO (RFC 2976)
  • AKA, AKA-v2 authentication (RFC 3310, RFC 4169)
  • ICE option tag (RFC 5768)
  • Message summary/message waiting indication (MWI,RFC 3842)
• Compliance, best current practices:
  • Issues with Non-INVITE transaction (RFC 4320)
  • Issues with INVITE transaction (RFC 4321)
  • Multiple dialog usages (RFC 5057)
  • SIP torture messages (RFC 4475, tested when applicable)
  • SIP torture for IPv6 (RFC 5118)
  • Message Body Handling (RFC 5621. Partial compliance: multipart is supported, butContent-Disposition header is not handled)
  • The use of SIPS (RFC 5630. Partial compliance: SIPS is supported, but still make use oftransport=tls parameter)

NAT Traversal

• STUN:
  • RFC 5389
  • Some RFC 3489 compatibility
  • DNS SRV resolution
  • short/long term authentication
  • fingerprinting
• TURN:
  • RFC 5766
  • DNS SRV resolution
  • UDP and TCP client connection
• ICE:
  • RFC 5245
  • host, srflx, and relayed candidates
  • aggressive and regular nomination
  • ICE option tag (RFC 5768)
• NAT type detection:
  • legacy RFC 3489
• Other:
  • QoS support on sockets (DSCP, WMM)