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Kamailio vs OpenSIPS: catalog facts
Kamailio	OpenSIPS
Free Free and open source under the GPLv2 or later.	Free Free and open source; paid training courses are offered separately.
Linux, Self-hosted	Linux, Self-hosted
Handles thousands of call setups per second WebSocket support for WebRTC plus TLS for secure signalling	Handles high SIP traffic volumes Covers many roles from PBX to load balancer
Infrastructure for engineers, not an end-user calling app Configuration requires solid SIP and VoIP knowledge	Steep learning curve, aimed at telecom engineers Signaling server only, not an end-user calling app
Downloadable app, Self-hosted	Downloadable app, Self-hosted
Open source	Open source
License: GPL-2.0-or-later	License: GPL-2.0
No account needed	No account needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked October 2, 2026	Official website Full listing and sources Checked October 2, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.