[Asterisk-Users] Sip behind the NAT

[Michael George]

On Tue, Dec 13, 2005 at 11:32:15PM -0500, Tom Rymes wrote:
> On Dec 13, 2005, at 8:25 AM, Michael George wrote:
> 
> >I have a similar problem with a client's system.  They have * 1.0.x
> >behind a NAT with all the SIP phones on the local network.  Their VoIP
> >provider is outside the NAT (a Metaswitch at their ISP, connected  
> >to the
> >phone lines from there).
> >
> >Their network guy has the firewall passing traffic on ports 5060 and
> >10000-20000 to the * system.
> >
> >I have externalIP and localnet set, but "nat=no" (default) is the case
> >for this one.
> >
> >Occasionally they will place outgoing calls and the other party  
> >does not
> >hear anything.  Usually another attempt at the call will pass audio
> >normally.
> >
> >One person who makes about 100 calls a day remembers having this  
> >happen
> >on about 7 calls one day.
> >
> >No one recalls this ever happening on incoming calls (though this  
> >client
> >primarily makes outgoing calls, I believe).
> >
> >Apparently this has been happening for a while and they just now
> >mentioned it to me.
> >
> >Would "nat=yes" in the general section of sip.conf make a  
> >difference in
> >this case?
> >
> >Is there anything else I could look at that might alleviate this
> >problem?
> 
> Without being a smartass, the only way to find out is to see if it  
> works. More obviously, if the Asterisk server has a NAT between it  
> and the ITSP, then use nat=yes, if it doesn't, then use nat=no. Of  
> course, if you set nat=no, then don't bother setting localnet or  
> externip, either.
> 
> Also keep in mind that some routers' "DMZ" settings still leave your  
> box behind NAT. They just forward all of the ports to the specified  
> address. (Linksys routers do this.)

I didn't detect any smartassity in your response...

I'm going to try nat=yes in the general section and then I'm going to
trim down the RTP port range just for fun and see what happens.

Thanks!

-- 
-M

There are 10 kinds of people in this world:
	Those who can count in binary and those who cannot.