External SIP User Showing Wrong Password

Hi,
I have recently installed a new server with Asterisk 1.6 to replace my 1.4 install. I have copied over the SIP accounts from my old working install however the two external sip users I have can not register. The are getting the following error

“[Oct 23 14:25:59] NOTICE[2419]: chan_sip.c:18227 handle_request_register: Registration from ‘5000 sip:5000@10.0.0.100’ failed for ‘94.140.3.210’ - Wrong password”

The passwords are definaly right as if I point them back to the old server they register without any issues.

Here is my Sip.Conf
[General]
Externip = 81.179.32.XXX
externrefresh=10
localnet = 10.0.0.0/255.255.0.0
nat=yes

[5000]
username=5000
secret=XXXXXX
type=friend ; Friends place calls and receive calls
context=dadhouse ; Context for incoming calls from this user
canreinvite=yes
;dial=SIP/5000
;subscribecontext=localextensions ; Only allow SUBSCRIBE for local extensions
;language=de ; Use German prompts for this user
host=dynamic ; This peer register with us
dtmfmode=inband ; Choices are inband, rfc2833, or info
;defaultip=94.140.3.210 ; IP used until peer registers
mailbox=5000@context ; Mailbox(-es) for message waiting indicator
subscribemwi=yes ; Only send notifications if this phone
;vmexten=voicemail ; dialplan extension to reach mailbox
disallow=all
allow=ulaw ; dtmfmode=inband only works with ulaw or alaw!
qualify=9000
nat=yes
port=5060

Any help would be great.
Cheers
Chris

check the registry line “user:pass@server”

Isnt that registry line used for sip trunks eg sipgate. This setup is just a standard user extension, infact it is a gigaset phone. There is no option on the gigaset to enter a registry line.

Thanks
Chris

What type of device is trying to register - is it a SIP phone or another Asterisk box?