[Freeswitch-users] Domain Question

I have a noobish question about setting up FS. I have it installed and running. I setup a soft client on the machine fs is on and point it to the ip address of the FS instance and it registers with no issues. I then setup an entry in my etc/hosts files "mydomain.localhost" and changed the domain in the soft client. The registration now fails. with the soft phone giving a 503 error "service unavailable" And I am watching the cli and I see no errors come through with the domain but I see it register with the IP :( I change it back to the ip address and it works. Any direction you guys could point me in would be great.