Self-hosted alternatives to Twilio
Per-minute and per-message pricing on infrastructure you could run yourself for a flat cost.
Below are 10 open-source projects that cover the same ground, each scored 0–100 on how actively it is actually maintained — commit volume, release cadence and recent trend. 4 of the 10 are currently rated healthy or better. Ordering reflects that score, not sponsorship.
| Project | Health | Activity (11 mo) | Stars | Licence | Last release |
|---|---|---|---|---|---|
| SIPCAPTURE Homer Troubleshooting and monitoring VoIP calls. | Healthy · 77 | 2k | AGPL-3.0 | 25 Sept 2026 | |
| Kamailio Modular SIP server (registrar/proxy/router/etc). | Healthy · 75 | 3k | GPL-2.0 | 16 Sept 2026 | |
| Asterisk Easy to use but advanced IP PBX system, VoIP gateway and conference server. | Healthy · 72 | 3.6k | GPL-2.0 | 17 Sept 2026 | |
| FusionPBX Web interface for multi-platform voice switch called FreeSWITCH. | Healthy · 72 | 1.1k | MPL-1.1 | 21 Sept 2026 | |
| FreeSWITCH Scalable open source cross-platform telephony platform. | Steady · 67 | 5.2k | MPL-2.0 | 28 Aug 2026 | |
| openSIPS SIP proxy/server for voice, video, IM, presence and any other SIP extensions. | Steady · 62 | 1.5k | GPL-2.0 | — | |
| Routr Lightweight SIP proxy, location server, and registrar for a reliable and scalable SIP infrastructure. | Steady · 57 | 1.7k | MIT | 7 Sept 2026 | |
| Flexisip Complete, modular and scalable SIP server, includes a push gateway, to deliver SIP incoming calls or text mess | Slowing · 43 | 189 | AGPL-3.0 | — | |
| 3CX Full-featured PABX system, with call queues, built-in web conferencing, live chat and social media messaging a | Unrated | — | ⊘ Proprietary | — | |
| Freepbx Web-based open source GUI that controls and manages Asterisk. | Unrated | — | GPL-2.0 | — |
How these were picked
Every project listed here is open source and can run entirely on hardware you control. We start from the categories that match Twilio's job — Communication - SIP — then rank by health score so that a popular-but-abandoned project never appears above a smaller one that is actively shipping. The scoring method is documented in full.
The scores are recomputed from repository data on every rebuild, so this page reflects the state of these projects as of 1 Oct 2026 — not the day it was written.
SIPCAPTURE Homer
Troubleshooting and monitoring VoIP calls.
Best fit: Network administrators and VoIP engineers who need to capture, store, and inspect SIP traffic for debugging purposes on their own infrastructure.
Worth knowing: The AGPL-3.0 licence requires you to make the source code available if you modify the software and offer it as a network service. Additionally, high-volume VoIP environments may generate significant storage and processing overhead for captured packets.
Kamailio
Modular SIP server (registrar/proxy/router/etc).
Best fit: Deploying a high-capacity custom SIP routing layer or registrar for enterprise voice architectures and telecommunication service providers.
Worth knowing: Configuration is notoriously complex and steep-learning-curve-driven, relying on a custom scripting language rather than standard configuration files.
Asterisk
Easy to use but advanced IP PBX system, VoIP gateway and conference server.
Best fit: It suits system administrators and telephony engineers who need to build custom voice communication infrastructure or private branch exchange networks from scratch.
Worth knowing: Configuring telephony routing and SIP trunks requires deep technical knowledge, and mistakes can result in misconfigured audio paths or security vulnerabilities like toll fraud.
FusionPBX
Web interface for multi-platform voice switch called FreeSWITCH.
Best fit: Administrators who want to deploy and manage FreeSWITCH setups without relying entirely on raw configuration files. It suits environments requiring multi-tenant voice routing.
Worth knowing: The Mozilla Public License 1.1 can present copyleft compliance challenges depending on how you modify and distribute the source code. It also inherits the steep configuration complexity of the underlying FreeSWITCH engine.
FreeSWITCH
Scalable open source cross-platform telephony platform.
Best fit: It suits developers and systems administrators building carrier-grade voice applications or custom private branch exchange setups from scratch.
Worth knowing: Telephony software of this nature carries a steep configuration curve and debugging SIP routing issues can become exceptionally complex in production.