Hi, first, I am since a very long time not working on the project anymore, so I'd recommend you move to using the Kamailio IMS, where the modules have been imported. Then regarding Early-IMS, there is no challenge, so something is probably not configured right. Early-IMS shall just identify the user by IP and directly answer with 200OK Then you're asking about the challenge, so not Early-IMS, but AKA. That part would be in the HSS, as that is where the Auth-Vectors are generated, not in S-CSCF, I...
As the error says, you probably don't have that FQDN in your domain, hence it is...
Pulled sip_router from iptel.org's CVS.
Fixed typo that could cause crash on P-CSCF wit...
Fixed dialog expirations:
Merged the 02_persistency branch into trunk r16...
Fixed possible bug in P_IPSec_relay().
Introduced terminate_s_dialog() method.