Asterisk – framework for building communications applications

Asterisk is an Open Source, Private Branch eXchange (PBX) and telephony toolkit. It is a hybrid TDM and packet voice PBX and IVR platform with ACD functionality. It is, in a sense, middleware between Internet and telephony channels on the bottom, and Internet and telephony applications at the top. However, Asterisk supports more telephony interfaces than just Internet telephony. Asterisk also has a vast amount of support for traditional PSTN telephony, as well.

Asterisk supports the following telephony hardware: All Analog and Digital Interface cards from Digium, QuickNet Internet PhoneJack and LineJack, any full duplex sound card supported by ALSA, OSS, or PortAudio, any ISDN card supported by mISDN on Linux (BRI), The Xorcom AstriBank channel bank, and VoiceTronix OpenLine products.

Asterisk has become a popular VoIP PBX worldwide.It’s technology and protocol agnostic.

There is a distribution available called AsteriskNOW, a Linux distribution that installs the operating system, Asterisk, drivers for Digium telephony cards and IP phones and an open source administrative user interface called FreePBX.

Features include:

  • Supports a wide range of video and VoIP protocols including the Session Initiation Protocol (SIP), the Media Gateway Control Protocol (MGCP), and H.323.
  • Supports most SIP telephones, acting both as registrar and back-to-back user agent.
  • Serve as a gateway between IP phones and the public switched telephone network (PSTN) via T- or E-carrier interfaces or analog FXO cards.
  • Caller ID.
  • Voice mail.
  • Conference calling.
  • Includes ConfBridge,  a high definition-capable conference bridge component that makes it easy to build stand-alone conferencing services or to integrate conferencing into other solutions, including IP PBX systems.
  • Directories.
  • Intercoms.
  • Interactive voice response (phone menus). Prompts are included with English, Australian English, Canadian French, Japanese, Russian, Mexican, Spanish, and Swedish.
  • Automatic call distribution.
  • Scripting with extensions languages including AGI.
  • Supports circuit-switching protocols such as ISDN and SS7.
  • Codeoc translation API.
  • Extended with its own API.

Website: www.asterisk.org
Support: Getting Started with Asterisk, GitHub, AstriCon
Developer: Digium, Inc.
License: GNU General Public License v2.0 / Proprietary

Asterisk is written in C. Learn C with our recommended free books and free tutorials.

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