Hi Ancuta,
i used SIP.js as a very simple Webfrontend, we even had the credentials hard-coded.
It must have been this commit: https://github.com/kamailio/kamailio/commit/5169e7dae017bdd4cb66dda388e78127...
It has been working both direction (WebRTC to IMS and IMS to WebRTC).
Thanks, Carsten