> -----Original Message-----
> From: Juha Heinanen [mailto:[EMAIL PROTECTED]
>
> Hadriel Kaplan writes:
>  > I know in the prefect world all UA's are "smart" and up on the latest
>  > specs and do the right thing.
>
> i didn't claim that all UAs are smart and implement latest specs.  but
> in most UAs, even in very old ones, it is possible to manually configure
> the reg int.  so if user's UA is behind nat, the user can usually
> configure reg int and make it work from behind nat.  on the other hand,
> very few old UAs support tcp.

Again I think this is an example of the different worlds of SIP usage meeting 
each other. :)

In my world, humans aren't typically expected to configure anything on their 
UA; short of maybe their AoR, username, and password.  And even that is 
sometimes pre-installed on the UA.

Furthermore, the registration interval is actually set to varying numbers, for 
example depending on transport.  And there are some proxies which actually have 
a mechanism to dynamically determine how long that interval should be based on 
the UAC's specific NAT, such that one UA using UDP might get 30 seconds for 
example, while another UA gets 120 seconds for UDP.

On the flip side, for the UAC's which try to be smarter by themselves: some of 
them send proprietary SIP request methods when they detect they're behind a 
NAT, or send proprietary message formats altogether which do not even comply 
with SIP request formatting rules.  Although to be fair those proprietary hacks 
mostly happen when UA's detect the registrar to be one from their own 
manufacturer, which never took into account a possibility that there could be 
proxies in the path between.

-hadriel
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