I really don't know technical details about uderlaying protocols, but configuring network interface is really thing I hate. Why? I use Ekiga on notebook and I often need to switch interface because I connect using ethernet, wifi or VPN.

Isn't there possibility to just listen on all interfaces or something simmilar?

Anyway the list of interfaces should be refreshed any time I enter settings dialog, so that I don't have to terminate program just to ensure it can see my newly configured interface.