I am pretty new to Asterisk and was wondering if I can get a little help.  I have read the basic guides but are still unable to recieve incoming calls - If i call my number the line rings disconnected or if I turn on voicemail from the VFX portal I get neil waka's VM.  I have turned on sip dubugging but see nothing in the logs so it is not hitting the Asterisk box at all.  I have also setup 2talk and can see incoming calls hitting the box so the ports I have forwarded (5060, 10000-20000) appear to be working fine.

I have tried entering the following information under sip.conf but when I run a ship show registry I get no attempt from VFX to register and it only show me 2talk's registered status.  I have now placed the information into users.conf (this is where 2talks working config has been entered) and it give me a status of sent but not registered as shown below:

users.conf

[general]
port=5060
dtmfmode=rfc2833
disallow=all
allow=g729
allow=ulaw
allow=alaw
registertimeout=20
regseconds=180

[VFX]
type=peer
fromuser=4_______7
host=pan.wxnz.net
insecure=invite,port
canreinvite=no
nat=yes
secret=6___________________c
username=F_____________________tz
register=4XXXXXX7:6XXXXXXXXXXXXnc:FbXXXXXXXXXXXXXXXtz@pan.wxnz.net/4XXXXXX7
context=incoming_calls

CLI<sip show registry
Host                            Username         Refresh State             Reg.Time                
pan.wxnz.net:5060        FbtnXXXXXXXC    120 Request Sent                                 
2talk.co.nz:5060           028XXXX86         05 Registered           Mon, 23 Mar 2009 09:51:26

I did not have to enter pan.wxnz.net into the hosts file as this is resolves ok unlike as.wxcnz.net.  I called Xnet tech support who said everything appears fine their end and it does not have to register so issue is at my end but I found another post where it appears it is showing to be registered so are now unsure if this is the case or not (obviously using a different host below):

CLI> sip show registry
Host                            Username       Refresh State                Reg.Time
as.wxcnz.net:5060               99500000           165 Request Sent         Sat, 26 Apr 2008 10:37:40


In my log file I get the following error:
WARNING[3142] chan_sip.c: Got 404 Not found on SIP register to service FbtXXXXXXXXXXXX1gtz@pan.wxnz.net, giving up

I have tried replacing the username with my VFX number without the leading 0 but this will not register and gives an error in the log saying:

NOTICE[3142] chan_sip.c: Failed to authenticate on REGISTER to '48XXXX57@pan.wxnz.net' (Tries 3)

I have not included any extensions.conf as i cannot even see xnet hitting the asterisk box while 2talk is.

Any help would be hugely appreciated.
Thanks.