Asterisk
Open-source framework for building communications applications.
At a glance
- Editor scoreNot yet scored
- PricingFree plan
- Best forLinux teams building a free voice platform
- Free planYes
- Paid fromNone
- Inbound callingYes
- Founded1999
- Facts checked19 Sep 2026
Where it wins
- Free and open source under GPLv2
- Covers IP PBX, VoIP gateways, SIP, conferencing, and dialplans
- Provides ARI, call recording, and outbound SIP provider connectivity
Where it doesn't
- Runs on Linux rather than across multiple listed platforms
- Does not supply verified phone-number support
- Requires users or system integrators to install and operate it
Our verdict on Asterisk
Asterisk is a free, open-source communications framework from Sangoma that turns a computer into a communications server. It is designed for developers and system integrators building IP PBX systems, business phone systems, VoIP gateways, conference servers, call distributors, and other real-time communications applications. Its Linux deployment model makes it a focused option for teams that want to build and operate their own voice platform rather than use a hosted telephony provider.
Its feature coverage spans core telephony construction: SIP channel support, inbound and outbound calling, dialplan-based call handling, call recording with MixMonitor, and outbound SIP registration for provider connectivity. Asterisk also supports REST API and WebSocket communications control through ARI, giving development teams a way to connect application logic with call control. These capabilities suit projects that need control over call flows, recording, conferencing, or provider connections, but they place more responsibility on the implementation team than a managed service would.
The main trade-off is operational scope. Asterisk is installed and operated by users or system integrators, and it runs on Linux. It does not supply verified phone-number support, so teams need to account for that part of their telephony design separately. Commercial licensing is available for some proprietary use cases, while the core project is distributed under GPLv2. Choose Asterisk if your team can manage a Linux communications server and wants an open-source foundation with broad IP telephony coverage. Choose another option if you need a hosted service or a platform that supplies phone-number support directly.
Asterisk pricing
Asterisk fact sheet
| Free plan | Yes |
|---|---|
| Paid from | None |
| Inbound calling | Yes |
| Outbound calling | Yes |
| Phone number support | Not verified |
| SIP support | Yes |
| Call recording | Yes |
| Concurrent call limit | Not verified |
| SDK languages | Not verified |
| Deployment | Desktop |
| Platforms | Linux |
| Pricing | Free plan |
| Website | asterisk.org |
| Facts checked | 19 Sep 2026 |
Alternatives to Asterisk
- Twilio Programmable VoiceA broad voice API for calling, IVR, SIP, recording, conferencing, and SDK-based apps.—
- Vonage Voice APIA broad voice API for building PSTN, SIP, WebRTC, IVR, and AI call workflows.—
- Twilio Elastic SIP TrunkingA focused SIP-to-PSTN service with secure trunking and pay-as-you-go voice charges.2.6
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