asterisk users - Feb 2006 - Asterisk, SIP phone , NAT

I have an asterisk pbx conected to internet. I need to connect to asterisk a
sip phone over the net that will be connected to the internet over a NAT
router. I found on the net that SIP is not very NAT friendly.  If somebody
has a how-to for my problem please share it with me . Also any experience in
this problem will be helpfull.
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Paul Lacatus wrote:
> I have an asterisk pbx conected to internet. I need to connect to 
> asterisk a sip phone over the net that will be connected to the internet 
> over a NAT router. I found on the net that SIP is not very NAT 
> friendly.  If somebody has a how-to for my problem please share it with 
> me . Also any experience in this problem will be helpfull.
> 
> -- 
> This message has been scanned for viruses and
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> 
Hi Paul,

in sip.conf

[123]
username=123
secret=123
type=friend
context=sip123
allow=all
host=dynamic
nat=yes
canreinvite=no
qualify=yes


The important ones are
host=dynamic - if the sip phone behind the nat is going to register on 
asterisk
nat=yes       - tells asterisk to not look to send packets back to the 
Ip in the SIP header, but the  IP in the IP header
qualify = yes
canreinvite=no

> nat=yes
> qualify=yes
That works, but it works better if you use a NAT/firewall box that can 
do "VOIP transformations" automatically. The Sonicwall TZ170 can do 
this. It rewrites the packets auto-magically so things "just work".
The
above parameters can be set to "no" then.

It seems to work more reliably that way, in my experience.


- Mike