August 2026 - sr-users - kamailio.org

WebRTC: One-Way Audio When Browser is Offerer (DTLS Role Question)
by Ricardo Castillo 07 Aug '26

07 Aug '26

Hi guys! I bring you a case that was experienced and resolved, and and some existential questions ;) Problem Summary (kamailio how registrar server and asterisk how b2bua) Scenario: Server-deployed WebRTC webphone making calls to another server-deployed webphone. Symptom: Bidirectional SIP signaling succeeds, but call initiator (offerer) has **no audio**. Answerer receives nothing; answerer can transmit fine to offerer. ## Investigation: What We Measured **WebRTC Internals dump from offerer side:** ``` dtlsState: "connecting" (never reaches "connected") packetsSent: 0 (DTLS never starts) iceState: "connected" (ICE nominates a pair, writable=true, RTT measured) ``` The second transport existed with old `rtcpMuxPolicy: negotiate`: ``` Transport 1: iceState=connected, dtlsState=connecting, packetsSent=0 Transport 2: iceState=new, dtlsState=new (unused, no candidates) ``` **SDP received by offerer (answer from Kamailio):** ``` m=audio 17070 UDP/TLS/RTP/SAVPF 8 126 a=rtcp:17070 a=rtcp-mux a=setup:passive ← THE QUESTION a=fingerprint:sha-256 [...] a=ice-ufrag:[...] a=ice-pwd:[...] a=candidate:... ← Asterisk's single candidate ``` **SIP signaling:** Fully correct. No errors, no retransmissions, clean 200 OK. **Hypothesis:** `DTLS=passive` in the answer (`onreply_route[REPLY_TO_WS]`) produces `a=setup:passive`. Per RFC 5763 §5, this assigns the offerer the **active DTLS role** ("send ClientHello"). But Chrome only sends the `ClientHello` if **it wrote** `a=setup:active` in its own SDP, not if the role was assigned via the answer. **The A→B→A Test:** 1. **A (baseline):** `DTLS=passive` → `a=setup:passive` → Offerer silent, `packetsSent=0` 2. **B (change):** `DTLS=active` → `a=setup:active` → **Offerer receives audio, `packetsSent > 0`** 3. **A' (revert):** `DTLS=passive` → `a=setup:passive` → Offerer silent again **Result:** Same Kamailio, same client, same network. Only the `DTLS=` flag changed. Audio works/fails with the flag. SOLUTION: ## What I Changed (The Fix) In rtpengine_manage I was use: DTLS=active **Effect:** - `DTLS=active` → RTPEngine emits `a=setup:active` in answer - Chrome receives `setup:active` → takes **passive** DTLS role (server) - RTPEngine initiates the DTLS ClientHello - Handshake completes, audio flows ----------------------- **Is this the expected behavior?** 1. Should `a=setup:passive` in an answer always work, or does it depend on the browser? 2. Is Chrome's behavior (only initiating if it wrote the role) documented in any spec? 3. Has anyone else seen this issue with server-deployed WebRTC webphones where the offerer is a modern Chrome? 4. Should the pattern be: **offer → delegate role (actpass), answer → assume initiative (active)**? best regards!! Ric

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Best approach for 2-node active-active Kamailio setup
by Asma BOUDDYACH 05 Aug '26

05 Aug '26

Hi , I am currently deploying a Kamailio SBC infrastructure with 2 nodes, one per datacenter, and I would like to set them up in active-active mode. I have no experience yet with multi-node Kamailio setups and I would like to ask: 1. What is the recommended approach for a 2-node active-active Kamailio deployment today? 2. What modules or mechanisms should I use to synchronize state between the two nodes (calls, registrations, etc.)? 3. Are there any known issues or limitations I should be aware of before starting the configuration? Any guidance or documentation pointers would be greatly appreciated. Best regards, -- This message and any of its attachments is intended solely for the addresses and is confidential. If you receive this message in error, please delete it and immediately notify the sender. Any use not in accord with its purpose, any dissemination or disclosure, either whole or partial, is prohibited except formal approval. The internet cannot guarantee the integrity of this message. The INTELCIA Group shall (will) not therefore be liable for the message if modified. ——————————————— Ce message et toutes les pièces jointes sont établis à l'intention exclusive de ses destinataires et sont confidentiels. Si vous recevez ce message par erreur, merci de le détruire et d’en avertir immédiatement l’expéditeur. Toute utilisation de ce message non conforme à sa destination, toute diffusion ou toute publication, même partielle, est interdite, sauf autorisation expresse. L’internet ne permettant pas d’assurer l’intégrité de ce message, le groupe INTELCIA décline toute responsabilité au titre de ce message, dans l’hypothèse où il aurait été modifié.

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Question regarding rtpengine packages in deb.kamailio.org repository
by Floimair Florian 03 Aug '26

03 Aug '26

Good morning! I have a question regarding the pre-built rtpengine packages hosted on deb.kamailio.org (https://deb.kamailio.org/rtpengine.html) Are these supposed to be up-to-date? I noticed that most of these are missing recent recent releases. E.g. the mr13.5 branch's latest build is 13.5.1.2 published on November 20th 2025. The most recent release on github shows 13.5.1.24 (released 3 days ago) Also the newest branch mr26 has 26.0.1.9 published on May 20th 2026 and github shows 26.0.1.21 I was under the impression that deb.kamailio.org now also builds and hosts the most recent rtpengine packages. If this assumption is wrong, please correct me. And if so: Is there another repo that hosts pre-built packages for rtpengine? I hope you can shed some light on this! Best regards Florian Floimair

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Getting started with Kamailio and Freeswitch
by Alex Lake 02 Aug '26

02 Aug '26

Hi all, I've been meaning to use this since it was called SER, but now is the time... I've tried to follow some guides on how to set it up. I created a user which seems to be able to REGISTER perfectly well. However, when I try to send a call, the 407 response seems to be replied to perfectly well, but it would appear that the lookup("location") function sets $rc to -3 and so Kamailio returns 404 to the INVITE. Any ideas about where to look for getting past this? Many thanks! Alex

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