Joe Abley wrote:
There's no useful way to use H.323 through a NAT though,
at least that I have seen working.
In enterprises this has never been a problem as H.323 works fine over
any kind of tunnel that goes over NAT and that's already there for other
purposes (VPN for example). I have multiple h.323 VOIP phones at home
over one IP address, one that is actually IPSEC encrypted.
As of SIP, Vonage does indeed use it so are many other SIP shops and it
works fine over NAT Vonage or not Vonage. I am not that familiar with
the Cisco ATA-186 (too pricey) but on other SIP phones such as the
popular $70 Grandstream if you know the IP address and port of the
remote SIP phone you want to join you can dial it directly.
Michel.
We use the Grandstream via sipphone.com for office to office calls.
It is using the RTSP. Just doing some cheap testing before we integrate
this into our Soft Switch, PBX and the PSTN.
The Sipphone has a "STUN" server function that makes doing SIP behind
NAT/PAT workable. I am a little hazy on its function as I am testing and
wanted the phones on public IP's. Seems to keep the NAT/PAT translations
constant by communicating with a remote server. Some users are doing SIP
with this phone without problems behind NAT/PAT.
james writes on 11/1/2003 2:30 PM:
The Sipphone has a "STUN" server function that makes doing SIP behind
NAT/PAT workable. I am a little hazy on its function as I am testing and
perhaps short for secure tunnel - an ssl tunnel that takes your sip traffic through http or something, and proxying them through a remote server?
srs
On mine I'm using for testing, if you turn NAT traversal on, and erase
the contents of the STUN field (don't leave them at 0.0.0.0, it'll
break), it does NAT traversal if the server supports it, without need
for a STUN server, which I still can't find a copy of. Fortunately it's
unnecessary. It works, as long as I don't try to contact another phone
behind another NAT.
-Paul
for a STUN server, which I still can't find a copy of. Fortunately it's
unnecessary. It works, as long as I don't try to contact another phone
behind another NAT.
That is the very essence of why I think NAT in the long run is a bad idea...
What good is a phone that can't contact another phone. One of the main
advantages to VOIP is that you can achieve some level of provider independence
and still have phone service. Sure, you need some level of ISP, but, you can
have more than one of those and SIP still works when one is down. If you
are dependent on a particular company running a proxy, then, if they hose
their stuff, you're out of luck.
Owen
Simple Traversal of UDP through NAT, for details see:
http://www.ietf.org/rfc/rfc3489.txt
and more generally
http://www.ietf.org/html.charters/midcom-charter.html
Bill.
- - -
Bill Owens
Manager, Network Development
NYSERNet, Inc.
Has anyone been experiencing connectivity issues with Wiltel over the
last 12 hours?
-brian