Replacing PBXes with Open Source

Kevin D. Clark clark_k at pannaway.com
Wed Aug 25 17:10:01 EDT 2004


"Ken D'Ambrosio" <kend at xanoptix.com> writes:

> Not sure... after all, you need the Internet infrastructure -- with a
> fair bit of bandwidth -- in place to take advantage of it.  I believe
> calls are ~80kb/s, including TCP overhead, which is a fair bit more
> than analog can cope with.

RTP nearly always gets transported over UDP.  The current thinking is
that TCP's congestion control don't mesh very well for time critical
data.

(note:  the signaling that occurs to setup a call is different than
the actual call itself -- these use different protocols)

> One question I have, though: how does H.323 cope with NAT, firewalls,
> etc., for incoming calls?  Anyone know?

Or SIP for that matter...  The answer is that some protocols handle
these, usually with a little bit of pain.  A lot of people who work in
this space wish that IPv6 would get deployed a whole lot sooner.

Regards,

--kevin
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