OPBX
OPBX: A free, open-source PBX for developers building configurable, self-hosted calling systems. Ranked #130 of 166 in Business Phone Systems by our editors (3.0/10); pricing: Free plan; best for developers building a free self-hosted calling system.
At a glance
- Editor score3.0 / 10
- PricingFree plan
- Best forDevelopers building a free self-hosted calling system
- Free planYes
- Paid fromFree
- Facts checked22 Sep 2026
Where it wins
- Free and open source with self-hosted deployment
- Custom routing, IVR, schedules, ring groups, and multi-tenancy
- Call records, campaigns, and real-time monitoring included
Where it doesn't
- Installation requires a Cloudonix CPaaS account
- Cloudonix usage may be separately priced
- Platform coverage centers on web, API, and self-hosted access
Our verdict on OPBX
OPBX is an open-source business phone system built on the Cloudonix CPaaS platform. It is designed for organizations, agencies, and service providers that need a configurable PBX application without managing SIP infrastructure directly. The system supports extension-to-extension calling, inbound and outbound routing, ring groups, IVR menus, business-hours schedules, holiday exceptions, direct inward dialing management, call records, outbound campaigns, and real-time monitoring. Its multi-tenant organization isolation and role-based access control also suit providers managing separate customer or organizational environments.
OPBX is free and distributed as a containerized application, with web, API, and self-hosted access options. The application exposes a REST API for administration and integration, which fits development teams that want to connect phone-system functions to their own workflows. Its routing controls cover simultaneous, round-robin, and sequential ring strategies, while IVR destinations can be configured around DTMF input. Call detail records support search, filtering, and CSV export, giving teams practical tools for reviewing call activity. Outbound campaign management and automated dialing extend the system beyond basic inbound phone handling.
The main ecosystem connection is Cloudonix CPaaS, and documented installation requires a Cloudonix CPaaS account. Cloudonix usage may be separately priced, so the free software does not necessarily mean that the complete operating cost is zero. OPBX is a strong fit for developers who value open-source control, custom routing, multi-tenancy, and self-hosted deployment. Organizations seeking a broader client ecosystem or a phone system centered on ready-made desktop and mobile applications should consider a different option.
Your product? Our editors can test OPBX in depth and publish a review, labelled as paid · from $149/mo →
OPBX pricing
OPBX fact sheet
| Free plan | Yes |
|---|---|
| Paid from | Free |
| Included users | Not verified |
| Business numbers | Not verified |
| Auto attendant | Not verified |
| Call routing | Custom |
| Voicemail transcription | Not verified |
| Desktop and mobile apps | Not verified |
| Deployment | Cloud, Self-hosted |
| Platforms | Web |
| Support | Tickets, Community, Docs |
| Built for | Small business, Mid-market, Enterprise (editorial estimate) |
| Integrations | 1 integrations: Cloudonix CPaaS |
| Pricing | Free plan |
| Website | developers.cloudonix.com |
| Facts checked | 22 Sep 2026 |
OPBX integrations
OPBX lists 1 integrations on its own site.
- Cloudonix CPaaS
Alternatives to OPBX
- RingCentral RingEXA broad cloud communications suite for established organizations with complex calling needs.9.1
- NextivaA broad business phone platform for teams that need calling, messaging, routing, and analytics.8.8
- Dialpad ConnectA unified business phone system with AI transcription, summaries, routing, and meetings.8.7
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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
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