https://9ne.pl/en/knowledge/ 2026-08-07T08:00:00Z Jarosław Starońhttps://9ne.pl/en/ https://9ne.pl/en/knowledge/webrtc-ice-stun-turn/ 2026-08-07T08:00:00Z 2026-08-07T08:00:00Z

How the browser chooses a media path, why a public candidate is not always enough and when TURN is necessary for a reliable connection.

https://9ne.pl/en/knowledge/technical-incident-root-cause-analysis/ 2026-08-07T08:00:00Z 2026-08-07T08:00:00Z

A good RCA does not seek someone to blame or merely recount events. It connects evidence, the failure mechanism, impact, correction and actions that prevent recurrence.

https://9ne.pl/en/knowledge/pbx-migration-without-disruption/ 2026-08-07T08:00:00Z 2026-08-07T08:00:00Z

A telephony platform migration needs parallel plans for configuration, registrations, routing, media, numbering, carriers and user behaviour.

https://9ne.pl/en/knowledge/one-way-audio-voip/ 2026-08-07T08:00:00Z 2026-08-07T08:00:00Z

One-way audio is not a single problem. It is a class of failures involving signalling, address translation, media routing, ACLs and device behaviour.

https://9ne.pl/en/knowledge/how-to-read-a-sip-trace/ 2026-08-07T08:00:00Z 2026-08-07T08:00:00Z

A practical method for analysing SIP signalling: from Call-ID and transactions, through routing and headers, to SDP, media and a precise RCA.

https://9ne.pl/en/knowledge/docker-nginx-tls-healthcheck-rollback/ 2026-08-07T08:00:00Z 2026-08-07T08:00:00Z

A lightweight production architecture for a web application: a locally accessible container, host Nginx, a certificate, readiness, versioned images and automatic rollback.

https://9ne.pl/en/knowledge/safe-production-server-migration/ 2026-08-07T08:00:00Z 2026-08-07T08:00:00Z

Migration does not start with copying files. It starts with an inventory, dependencies, acceptance criteria and a practical way back.