[*] [on-asterisk] 3CX and non Asterisk PBX users.

[Sean Walberg]

Most firewalls have a hard time with relating UDP flows, so I don't know if
it's a case of Cisco being more or less braindead than other vendors.

The other possibility is that the 9971 came from an acquisition or was built
as part of a partnership, in which case someone else might have made the
"hey, why don't we use TCP!?" decision.

Sean

On Wed, Dec 29, 2010 at 12:55 PM, John Lange <john at johnlange.ca> wrote:

> Sorry to revive a stale thread but I've been doing some work recently
> with the Cisco 9971 phone and interestingly this phone is TCP only for
> both SIP and RTP.
>
> Since Microsoft and Cisco are both doing VOIP TCP I'm curious if there
> is actually a good reason for this or if it's just a case of the blind
> leading the blind?
>
> As I said previously in this thread, SIP TCP _might_ make some sense
> as long as you stripped the state tracking out of the SIP protocol
> (which means it wouldn't actually be SIP anymore) but RTP over TCP?
> Madness!
>
> I can think of only two reasons for this:
>
> a) Microsoft doesn't know jack about SIP/RTP so they wrote it using
> TCP because they didn't know any better & Cisco wanted to be
> compatible with Microsoft.
>
> b) Cisco firewalls aren't good at reliably tracking UDP state so they
> decided to get around the problem by using TCP.
>
> If there is actually a good technical reason for voip over TCP I'd
> love to hear it.
>
> --
> John Lange
> www.johnlange.ca
> _______________________________________________
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> Asterisk at muug.mb.ca
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>



-- 
Sean Walberg <sean at ertw.com>    http://ertw.com/
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