SPA-2102 sending local IP instead of WAN IP in SIP packets

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On 10/06/2010 02:50 PM, bruce bruce wrote:
> Hi Guys,
> This is such an annoying issue whenever it comes up. The sender and
> receive always receive the source public IP no matter what in the IP
> packets but then SIP packets go out with something like
> In this instance, a Bell Canada DSL modem is installed and I saw the
> SPA-2102 register properly but only to fail later on due to sending it’s
> LAN IP to the Asterisk server.
> So, I put NAT=yes and NAT_ALIVE=yes but that didn’t help at all. I also
> put the device on DMZ in the Bell Canada DSL modem and still the same issue.
> I am wondering when would manufacturers finally fully comply the SIP RFC?!

Exactly how is this behavior non-compliant with “the” (sic) SIP RFC?
There is nothing in any SIP RFC that mandates that a SIP UA must be
aware of multiple IP addresses over which it can be reached, and select
the proper one to include in SIP requests and responses.

In fact, many SIP UAs, Asterisk included, work just fine behind NAT
devices without ever knowing what their external IP addresses are.

If you had actually described how the device failed, we might be able to
tell you what you could do to resolve the problem. In general, Asterisk
works just fine with endpoints that are behind NAT devices and never
send their external IP addresses in their SIP messages… there are
probably millions of devices working that way every day.