Maybe Kamailio could report an error in the logs when the unrecognised transport type is submitted?

That could be handy. I am not sure how/where to put something like this though.

Interesting, I had those routing problems initially, so I added the add_contact_alias() to my script but only if if (nat_uac_test(64)) passes. I'll take a look at what is happening here.

It just occurred to me that as you are passed the point that handle_ruri() alias is called so you wouldn't see this in the request outside Kamailio. So please ignore my comments on this part.

I am using the latest 4.0.0 sources, so I guess I could also switch to outbound.

That's probably a good idea as long as you have separate edge-proxies and registrars (always a good idea to begin with). Outbound is the recommended method for SIP over WebSocket.

Regards,

Peter

-- 
Peter Dunkley
Technical Director
Crocodile RCS Ltd