Freedom251
For vendors
AdvertiseTop spots, featured rows, home sponsor Get listedAdd a product we don't cover yet Claim a listingFree: verify the domain, then correct your page Vendor dashboardNumbers, orders and placements
Vendor dashboard
No. 5 of 20 ·Interactive Voice Response Software

Asterisk

Linux · Self-hosted · API

Visit site Alternatives

Freedom report

Two barsScore 6.3

  • Free tierA free tier is on its own pricing page
  • Open codeNo open-source code on record
  • Runs widely1 of 6 device platforms
  • DocumentedPlans, terms and facts published

Asterisk is a free, open-source framework for building communications applications that can turn an ordinary computer into a communications server. It powers 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. Its computer-telephony interfaces include AGI, AMI and ARI, and supported VoIP protocols include SIP, H.323, IAX, Jingle/XMPP, MGCP and SCCP. Asterisk can connect communications to applications, including CRM systems using AMI. The source code can be downloaded, and the project points users toward installation on a modern cloud Linux instance. Building applications with it requires working knowledge of Linux, scripting, networking and telephony. Asterisk is distributed under GPLv2; Sangoma offers commercial licensing for uses incompatible with that license. Sangoma also offers five support levels for core components of current open-source versions, while the Asterisk forum provides community help. MFC-R2 is not supported, though a patch is available.

Who it is for

Asterisk suits people building communications systems who have working knowledge of Linux, scripting, networking and telephony. It can also suit teams connecting telephony to applications or CRM systems through its interfaces.

What is good

  • Free, open-source framework under GPLv2
  • Supports call routing, recording and conferencing
  • Includes AGI, AMI and ARI interfaces
  • Supports SIP and several other VoIP protocols

What to know first

  • Requires Linux, scripting, networking and telephony knowledge
  • MFC-R2 is not supported
  • Commercial licensing may be needed for incompatible uses

Verdict

Asterisk provides a broad framework for building communications systems, with multiple interfaces and VoIP protocols. It is a better fit for technically capable builders than readers seeking a ready-made calling service.

Asterisk plans and pricing

All plans
Asterisk Free Free and open source · GPLv2 · download free of charge asterisk.org · 4 Oct 2026

Compared on interactive voice response software

Free plan
Yes

Best Asterisk alternatives

See all 19
Two bars FreeSWITCH Free tier No. 1Free6.5 One bar Voicent Free tier No. 2$179/mo6.5 One bar Telnyx Text-to-Speech API Free tier No. 3$500/mo6.4 One bar Twilio Studio Free tier No. 4Free6.4 No signal Telnyx TeXML Paid plans No. 6$500/mo6.3 No signal Plum DEV Paid plans No. 7—5.4