Thoughts from Paul as { paul(_dot_)jones(_at_)ties(_dot_)itu(_dot_)ch } begin
with ">"
those from myself with ">" { dank(_at_)hq(_dot_)lindsayelec(_dot_)com }
Thanks for your thinking. I don't want to overburden this list with items
which might best be discussed elsewhere, so if there is a perception this
goes on and on, just email me and I'll move it to a more private space. I
really appreciate Paul's responses as below. Thank you.
In reacting to my comment H.323 has "done poorly" Paul said:
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.
I wonder how many IP "telephony" (multimedia conferences featuring voice
primarily) are in use. For instance AT&T broadband have about 850K broadband
(ie CATV) circuit switched phones in the USA. I agree with the above,
especially since it has to be the most widely used as it is really the only
one that exists at all! I mean its not, at least at this time, what the
computer industry calls a "killer app".
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.
Effectively, Microsoft Messanger Version 4.XX running under WIN 2000 or Win
XP is essentially free. Its mildly maimed as a strategy. I think this is
"fair" but wonder if it strickly conforms to SIP, as far as that standard is
promulgated. "poorly" is a troublesome term. I guess, relative to what? When
we tried to use it here it worked with minimal effort on one side of our
firewall(s). But the effort to support it port usage seemed high. Generally,
few firewalls seems able to support the >1024 very abstract port usage H.323
requires. Also, if the computing entities want to help H.323, for instance
with RSVP QoS, source routine, etc its hard for them to know which port is
H.323 without snooping at a very low level. I discern this situation.... I
do not know this is true for sure. Its what the various firewall expert(s)
have said about H.323 Of course Peter is right the next big thing in this
field is 2Q away in time and that's what Microsoft does.
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.)
Neither of us know the future, but I think I'm inclined to *not* agree. I
think for $0 calling globally millions of PC users will put up with latency,
for casual use; (like voice while playing X-Box, PS2 games, etc). Also, the
present universe for high speed connections for instance, at home is around
10% (>200 kBit/Sec): xDSL, CATV, ISDN. This might be near, but still under
critical mass. Your right again in saying "many people will not even use
it". My issue is the many tens? of millions who will if they can get it to
work at all!
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
The wwwpacketizer.com site assoc with Paul is an amazing resource in this
field. I've spend the last 3 hours reading RFC 2543 on SIP and it seems like
it has a lot of heavy duty good thinking in it. I should read the similiat
H.323 documents.
I do cable TV and where I consult that's what we do here in general.
Thanks for the info and I am going to read the packetizer site in some detail.
regards to all
Dan