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Asterisk
What it is
Asterisk is a free, open-source framework for building communications applications; it can turn an ordinary computer into a communications server. It is used to power IP PBX systems, VoIP gateways, conference servers, call centers, voicemail servers, and IVR systems. Listed functions include call routing, recording, queuing, conferencing, voicemail, automated attendants, and call transfers. Computer-telephony interfaces include AGI, AMI, and the Asterisk REST Interface (ARI). Supported VoIP protocols include SIP, H.323, IAX, Jingle/XMPP, MGCP, and SCCP. Asterisk can connect communications to applications, including CRM systems through AMI. The source code is downloadable, and the project points users toward installation on a modern cloud Linux instance. Building applications with Asterisk requires working knowledge of Linux, scripting, networking, and telephony. It is distributed under GPLv2; Sangoma offers commercial licensing for uses incompatible with that license. Community assistance is available through the Asterisk forum.
For and against
For
- Free and open source under GPLv2.
- Supports SIP and several other VoIP protocols.
- Includes call routing, recording, and conferencing.
- Offers AGI, AMI, and ARI interfaces.
- Community forum offers installation and upgrade feedback.
Against
- Building applications requires Linux and telephony knowledge.
- MFC-R2 is not supported, though a patch is available.
- Commercial licensing may be needed for GPLv2-incompatible use.
The verdict
Asterisk provides a broad framework for building communications servers and related applications. Its Linux and telephony requirements make it a more suitable fit for technically experienced teams.
Who it suits
Asterisk suits developers and organizations building communications systems who have working knowledge of Linux, scripting, networking, and telephony. It can serve projects needing PBX, VoIP, call-center, or IVR functions.
Plans and prices
Asterisk
Free and open source · GPLv2 · download free of charge
Read 4 Oct 2026 · asterisk.org
On the record
- Community help
- The Asterisk forum offers community help and feedback on installation, upgrading and running Asterisk.asterisk.org · read 4 Oct 2026
- Deployment
- Asterisk can be downloaded as source code, and the site points users to install it on a modern cloud Linux instance.asterisk.org · read 4 Oct 2026
- Features
- Its listed features include call routing, recording, queuing, conferencing, voicemail, IVR, automated attendants and call transfers.asterisk.org · read 4 Oct 2026
- Integrations
- The site says Asterisk can connect communications to applications, including Salesforce automation or CRM systems using AMI.asterisk.org · read 4 Oct 2026
- Interfaces
- Computer-telephony interfaces include AGI, AMI and the Asterisk REST Interface (ARI).asterisk.org · read 4 Oct 2026
- Licensing
- Asterisk is distributed under GPLv2 and Sangoma offers commercial licensing for uses that are incompatible with GPLv2.asterisk.org · read 4 Oct 2026
- Linux requirement
- The site says building applications with Asterisk requires working knowledge of Linux, scripting, networking and telephony.asterisk.org · read 4 Oct 2026
- Notable limitation
- MFC-R2 is listed as not supported, although the page says a patch is available.asterisk.org · read 4 Oct 2026
- Protocols
- Listed VoIP protocols include SIP, H.323, IAX, Jingle/XMPP, MGCP and SCCP.asterisk.org · read 4 Oct 2026
- Purpose
- Asterisk is an open source framework for building communications applications and turns an ordinary computer into a communications server.asterisk.org · read 4 Oct 2026
- Sponsor
- Asterisk is sponsored by Sangoma.asterisk.org · read 4 Oct 2026
- Support
- Sangoma offers five support levels for core components of current open source Asterisk versions, with Level 5 reserved for customers requiring an SLA and engineering support.asterisk.org · read 4 Oct 2026
- Use cases
- Asterisk powers IP PBX systems, VoIP gateways, conference servers, call centers, voicemail servers and IVR systems.asterisk.org · read 4 Oct 2026
