Difficult Geting SIP To work outside of LAN

Hi Guys,
I have Asterisk 1.4 running on Fedora Core 8. My clients on the internal network and communicate successfully. However, I’m attempting to get a few external users with laptop to be able to connect to the server however, they are not being able to do that. I have edited the SIP.conf file and made the following adjustments.
externhost = host.domain.com
externip = x.x.x.x
localnet = x.x.x.x/x.x.x.x
nat = yes
port = 5060
disallow = all
allow = ulaw
allow = alaw
alow = g729
allow = gsm
qualify = yes

In addtion, I ensure on the user the NAT option is ticked in the asterisk-gui config.

Also below is a short capture from Wireshark. Can anyone tell me what is wrong here.
Protocol SIP Request: REGISTER sip:domain
SIP Status: 100 Trying (1 bindings)
SIP sTATUS: 401 Unauthorized (o bindings)

P.S. The same accounts that work internally are reporting errors when I try to access the system from outside the LAN.


i think you need to check following things
1.it may be NAT issue so check device may be router which connected to outside internet for all voip ports liek 5060
2.extrenip= is the ip of that external device which communicate with out side world
3. in sip.conf geanreal u need to set bindaddr= & localnet = ur local gateway ip not asterisk server ip
4.on asterisk server plz check iptables file for all the needful port
5.also check whther that outside user trying with invalid username & passwotd?
6.in such case out side user device config also diffrent as your Asterisk is on localnet. so check all thsi clrealy.


& yes in your user config in sip.conf