Dan,
H.323 has not done poorly. In fact, it is the most widely used
standards-based call control protocol. The largest chunk of VoIP traffic
in the world is carried over H.323-based networks. Even now, H.323 is
finding new markets that SIP has only begun to touch. SIP is missing a
number of critical components necessary to really make it carrier-class.
There are many misunderstandings about H.323 and most companies didn't
care: after all, they were out selling H.323 products very well and
ignored the incorrect marketing hype.
So, the entire paragraph about "this standard did poorly" is false and
"SIP looks like a winner" is likewise false. That's not to say that SIP
is a failure: it's just that it has not met with the same market success
as H.323 (yet-- I suspect it will one day). Definitely, Microsoft is
planning to roll it out in XP and that will excite a few people. At the
same time, it will put a few companies out of business as Microsoft's SIP
proxy will become the defacto-standard. I have not seen pricing, but I
would bet it will be extremely inexpensive.
The result of this roll-out will force many out of business or force them
to change their business strategy. Because the Internet is a poor medium
for IP Telephony, many people will not even use it.. just as few used
NetMeeting for VoIP. What usage it got was primarily for data
capabilities. Of course, there will be some usage, but I suspect that
most VoIP traffic will still come from dedicated hardware (IP phones,
residential GWs, infrastructure equipment, etc.)
Supporting H.323 through a firewall is not terribly complex and SIP
suffers from the same problem: layer 3 addresses are carried in the
application layer. These are quite comparable.
For a more thorough comparison of H.323 and SIP, visit:
http://www.packetizer.com/iptel/h323_vs_sip/
Best Regards,
Paul
On Wed, 15 Aug 2001, Dan Kolis wrote:
Greetings,
I'm trying to put together a programme regarding multimedia telecom and have
been working with H.323.
My perception is this standard did poorly due to generally insufficient
bandwidth, a small universe of QoS and hard to support port usage.
On the other hand, SIP looks like a winner the same way bluetooth did. That
is, the blemishes only show when the thing exists.
Supporting H.323 through a firewall/proxy seems intrinsically difficult. On
the other hand, the wildcard port usage might have subtle value in
scalability. I gather SIP is more old school, like a telnet session, more or
less containing more complex objects; (speech, etc).
Any opinions on this?
I'm not complaining but am observing the zero length attached viruses in my
attachment directory from this list just passed 100!
Regards to All
Dan K