CSipSimple is a Voice over Internet Protocol (VoIP) application for Google Android operating system using the SIP

Session Initiation Protocol

The Session Initiation Protocol is an IETF-defined signaling protocol widely used for controlling communication sessions such as voice and video calls over Internet Protocol . The protocol can be used for creating, modifying and terminating two-party or multiparty sessions...

.

It is open source

Open source

The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...

 and free software

Free software

Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...

 released under the GNU General Public License

GNU General Public License

The GNU General Public License is the most widely used free software license, originally written by Richard Stallman for the GNU Project....

. As of mid-2011, reviews are favorable.

It relies on the pjsip SIP stack and get features provided by this sip stack.

The key features of this software are:

• Multi-codec support: Speex
  Speex
  Speex is a patent-free audio compression format designed for speech and also a free software speech codec that may be used on VoIP applications and podcasts. It is based on the CELP speech coding algorithm. Speex claims to be free of any patent restrictions and is licensed under the revised BSD...
  
   (narrow band, wideband), G.711
  G.711
  G.711 is an ITU-T standard for audio companding. It is primarily used in telephony. The standard was released for usage in 1972. Its formal name is Pulse code modulation of voice frequencies. It is required standard in many technologies, for example in H.320 and H.323 specifications. It can also...
  
   (u-law, a-law), GSM, iLBC
  ILBC
  Internet Low Bitrate Codec is an open source royalty-free narrowband speech codec, developed by Global IP Solutions formerly Global IP Sound . It was formerly licensed as a freeware with limited commercial use, but since 2011 it is available under an open source license as a part of the open...
  
  , SILK
  Silk
  Silk is a natural protein fiber, some forms of which can be woven into textiles. The best-known type of silk is obtained from the cocoons of the larvae of the mulberry silkworm Bombyx mori reared in captivity...
  
   (narrow band, wideband, ultra wideband), G.722
  G.722
  G.722 is a ITU-T standard 7 kHz wideband speech codec operating at 48, 56 and 64 kbit/s. It was approved by ITU-T in November 1988. Technology of the codec is based on sub-band ADPCM ....
  
  
• Can use native audio driver
• STUN
  STUN
  STUN is a standardized set of methods, including a network protocol, used in NAT traversal for applications of real-time voice, video, messaging, and other interactive IP communications....
  
   and ICE NAT
  Nat
  Nat or NAT may refer to:* Nat., an abbreviation for Natural* Nat , a Burmese spirit worshipped in Myanmar in conjunction with Buddhism...
  
   traversal
• Integration with Android operating system with filters and rewriting rules
• A distribution of the software available on the website allow SRTP
  SRTP
  In Communications:* Secure Real-time Transport Protocol, security profile for Real-time Transport Protocol* Service Request Transport Protocol GE-Fanuc Automation Protocol for Programmable logic controller use.* Student Research Training Program...
  
  , SIP over TLS and ZRTP
  ZRTP
  ZRTP is a cryptographic key-agreement protocol to negotiate the keys for encryption between two end points in a Voice over Internet Protocol phone telephony call based on the Real-time Transport Protocol. It uses Diffie-Hellman key exchange and the Secure Real-time Transport Protocol for...
  
  
• SIP-SIMPLE messaging

See also

• Comparison of VoIP software
  Comparison of VoIP software
  VoIP software is used to conduct telephone-like voice conversations across Internet Protocol based networks. VoIP stands for "Voice over IP". For residential markets, VoIP phone service is often cheaper than traditional public switched telephone network service and can remove geographic...
  
  
• List of SIP software
• Mobile VoIP
  Mobile VoIP
  Mobile VoIP or simply mVoIP is an extension of mobility to a Voice over IP network. Two types of communication are generally supported: cordless/DECT/PCS protocols for short range or campus communications where all base stations are linked into the same LAN, and wider area communications using...