ZyXEL Communications P-2000W V2 - Manual (Page 10)

P2000W V2 Troubleshooting Guide
All contents copyright (c) 2005 ZyXEL Communications Corporation.
2. How can I check if problem is cause by NAT or not?
There may not be an easy or quick answer to this question. One of the best
way to see if the problem is cause by NAT or not is to put P2000W V2 on
public network, (With public IP and no NAT) see if it work under such
condition.
If you it can work on public network but can not work behind NAT than very
likely your NAT gateway is not supporting SIP pass-through. In such
condition you will need to consult your NAT router vendor for resolution.
3. If I've confirmed it is an NAT problem. What should I do?
If you are certain or confirmed the problem is caused by NAT you need to
check the following.
1. Check if your NAT router vendor supports SIP pass-through.
2. If the NAT router does not support SIP pass-through, you need to consult
your ITSP support if they support SIP outbound proxy. Since different NAT
router vendor implement NAT differently. Typically ITSP may provide SIP
outbound proxy to resolve NAT pass-through issues as sip proxy does not
require the SIP client to do any modification as the server will modify the SIP
message content according to the your WAN IP it sees. If your ITSP
supports outbound proxy you need to obtain the configuration and configured
the outbound proxy location on P2000W V2.
3. As mentioned some NAT may not be SIP friendly. ITSP may support
STUN instead of SIP outbound proxy to resolve this issue. To use STUN sip
client must support STUN client. How STUN work is when the user register
the server will tell SIP client what the WAN IP the server sees from the SIP
client and SIP client will use this IP as SIP content to identify its location.
4. Unable to register with the SIP server?
If you are unable to register with SIP server.
1. Make sure the Internet is reachable and the SIP register server is
reachable. If your register server uses domain name make sure DNS
name can be resolved.
2. Make sure the SIP account is correct and the password is correct.
3. Check if there is NAT router before it. If there are NAT router before it
follow troubleshooting step above to verify if NAT is the cause of the
problem.