Error registering SIP trunk: "No Authentication"

Hi everyone,
I’m trying to configure a SIP trunk in Asterisk, this is an extract of my sip.conf file:

[general]
port=5060
bindaddr=0.0.0.0
;externip=188.218.155.110
context=incoming
nat=force_rport,comedia
localnet=172.16.0.0/255.255.0.0
localnet=192.168.255.0/255.255.255.0
allowguest=yes
insecure=port,invite
faxdetect=cng
;t38pt_udptl = yes
callevents=yes
language=it
allowsubscribe=yes
dtmfmode=rfc2833
defaultexpiry=180
registertimeot=60
registerattempts=10
rtpkeepalive=15
rtptimeout=20
rtpholdtimeout=300
disallow=all
allow=alaw
allow=ulaw


register => MYUSERNAME:MYPASSWORD@ims.tiscali.net/MYUSERNAME


[01158494XX]
context=incoming
type=peer
host=ims.tiscali.net
secret=MYPASSWORD
;port=5060
insecure=port,invite
username=MYUSERNAME
;usereqphone=yes
user=MYUSERNAME
fromuser=MYUSERNAME
realm=ims.tiscali.net
fromdomain=ims.tiscali.net
qualify=yes
;nat=force_rport,comedia
directmedia=yes
outboundproxy=94.32.130.112
sipdebug=yes
srvlookup=yes
trustrpid=yes

After a first try, Asterisk was warning me that it couldn’t resolve “ims.tiscali.net” . Since the ISP gave a specific about the proxy server to use:

srv: srvmi.p.ims.tiscali.net
fqdn:core2.p.ims.tiscali.net
IP: 94.32.130.112

I decided to force the routing: on the pbx, i edited the host file adding the line:

94.32.130.112 ims.tiscali.net

After reloading, I don’t get the error on the resolving of the domain anymore, but in the sip show registry, the sip trunk was marked as “No Authntication”, while before the file edit was marked as “Failed”.

Can someone help me troubleshoot this issue?