I will change the stun server in the omponents/Phone/IAX/JingleIax.tcl and will see whether this fixes my problem with the phone call in one of the next days. However, on the Windows box, which is not mine, I only have a large coccinella binary, so I can only change it on the OpenBSD box.
My ejabberd server is a ejabberd-2.0.1, which doesn't have STUN server yet. It seems the STUN server is available from ejabberd 2.1.X, so I'll need to update this one before my server can act as a STUN server. However, waiting to the end of the month for OpenBSD 4.6 doesn't makes sense, because there in the ports is ejabberd-2.0.3 only. I have to update manually anyways.
I'll take a look at XEP-0215, despite it is still only marked as Experimental, ;) Howevery, it makes much more sense, to automatically detect any stun server for usage, than hardcoding one in the source ;)