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|Initial release||9 January 2010|
1.02.03 / 30 November 2014
|Written in||Java, C/C++|
|License||GNU General Public License|
CSipSimple is a Voice over Internet Protocol (VoIP) application for Google Android operating system using the Session Initiation Protocol (SIP). It is open source and free software released under the GNU General Public License.
In October 2017, the project is abandoned. On or before May 26, 2019 CSIP no longer has an active website and is no longer available on the Play Store. Users with CSip already installed did not have the app removed from their device.
The key features of this software are:
- Multi-codec support: Speex (narrow-band/wide-band), G.711 (u-law/a-law), GSM, iLBC, G.729 (support dropped with r2180, need to buy a licensed g729 plug-in), G.722, AMR (narrow-band), iSAC, SILK (narrow-band/wide-band/ultra wide-band) (support dropped in 2014)
- A plug-in adds support for Codec2, G.726, G.722.1 and Opus
- A plug-in adds video calling with VP8, H264 and H263-1998 codecs
- Multi-account support: up to 10 accounts can be activated at the same time
- Can use native audio driver
- NAT traversal using STUN, TURN and ICE
- Integration with Android operating system with filters and rewriting rules
- Security and encryption with SRTP, SIP over TLS 1.0 and ZRTP
- SIP SIMPLE messaging
- An API for third party applications is available 
- Packet loss concealment (PLC) using PJSIP
- Support for IPv6 - If the hardware, Android version, ISP and all other parts of the connections involved can handle IPv6, then Csipsimple can be used to make direct end-to-end ipv6-to-ipv6 calls.
- "CSipSimple nightlies". Archived from the original on 26 March 2012. Retrieved 8 April 2012.
- "CSipSimple". Google Code. Retrieved 22 August 2011.
- "CSipSimple "OpenSource SIP", for Android". IPComms. IP Communications. Retrieved 22 August 2011.
- Project abandoned – CSipSimple – GitHub.
- "SIP and Media Features". pjsip.org. 12 December 2007.
- "Javadoc of CSipSimple API". r3gis3r. 8 April 2012.
- Michael (7 January 2011). "OneSuite on Android Using CSipSimple". Perk Up. OneSuite Blog.
- "CSIP Simple: Mobile SIP Client for Android". OnSIP. Junction Networks. 5 May 2011. Archived from the original on 11 August 2011. Retrieved 22 August 2011.