This is due to stun.ekiga.net being down - see http://mail.gnome.org/archives/ekiga-list/2009-October/msg00164.html Since Ekiga requires registration to a STUN server, it might be a good idea if there was a STUN server running on the same machine as the registration server, for reliability.
Attachment:
signature.asc
Description: OpenPGP digital signature