Switching to H.245

Francois Audet audet at NORTELNETWORKS.COM
Thu May 17 15:14:54 EDT 2001

Hum, interesting.
My follow up question is then:

*       A sends SETUP to B with fast start with h245Address and tunnelling.
ALERTING responds to FS, and the whole TCS and M/S process takes place. Then
A wants to forward the call (internally) before answer (i.e., in the
ALERTING phase). It thus sends TCS=0, TCS=full, OLCs and all that. Then B
answers and sends the CONNECT (with the same fastStart as the ALERTING as
per earlier discussions we had ;^)  Wouldn't the content of the fastStart
contradict what the actual forwarded connections is really? Would it be a

Seems pretty tricky...

-----Original Message-----
From: Paul Long [mailto:plong at IPDIALOG.COM]
Sent: Thursday, May 17, 2001 11:52 AM
Subject: Re: Switching to H.245

I realize how this could be confusing, but I don't necessarily see a
conflict since they all say, "may." For example, if I say, "X may do A or
B," and, "X may do B," that does not preclude "X may do A." Conversely, if I
said "shall" instead of "may," I think there would be real conflicts. I've
worked on EPs that are very aggressive during call establishment. For
example, Setup contains an h245Address and indicates support for Fast
Connect and H.245 Tunneling. Other than all the non-compliant EPs out there,
it worked just fine. The EPs also support third-party pause, but I don't
remember ever testing that particular scenario. As long as an EP is
implemented correctly, I don't see anything in the Recommendation that would
prevent this from working.
Paul Long
ipDialog, Inc.

-----Original Message-----
From: Mailing list for parties associated with ITU-T Study Group 16
[mailto:ITU-SG16 at mailbag.cps.INTEL.COM]On Behalf Of Francois Audet
Sent: Thursday, May 17, 2001 1:07 PM
To: ITU-SG16 at mailbag.cps.INTEL.COM
Subject: Switching to H.245

H.323/ says :

After establishment of a call using the Fast Connect procedure, either
endpoint may determine that it is necessary to invoke call features that
require the use of H.245 procedures. Either endpoint may initiate the use of
H.245 procedures at any point during the call, using tunnelling as described
in 8.2.1 (if h245Tunnelling remains enabled) or a separate H.245 connection.
The process for switching to a separate H.245 connection is described in

8.2.3 says:

When H.245 encapsulation or Fast Connect is being used, either endpoint may
choose to switch to using the separate H.245 connection at any time.

There seem to be some contradiction in there: is it "after establishment" or
"at any time"?
Do you have to wait for after CONNECT to establish a separate H.245 channel
or not?
The case I'm interested in would be to send SETUP with fastStart, then
receive ALERTING with fastStart. Then can either end initiate H.245  before
CONNECT? If so, what if third party pause and redirection  is initiated
before CONNECT?
François AUDET, Nortel Networks
mailto:audet at nortelnetworks.com <mailto:audet at nortelnetworks.com> , tel:+1
408 495 3756

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