Re: Fax send/receive procedures

I do agree to Gunnar.
 
You've to consider both E2E T.30 sequences & H.248 signalling.
There might be race conditions at both H.248 interfaces, but their final
resolution (i.e. which G3FE may sent) is up to T.30 IMO. 
 
Albrecht
 
PS
I've Cc'd the T.3X experts from Q.14/16.
 
________________________________

From: [email protected] [mailto:[email protected]] On Behalf
Of Gunnar Hellstrom
Sent: Dienstag, 6. Januar 2009 21:51
To: 'Andre Rosa Stefanini'; [email protected]
Cc: 'Alexandre de Brito Matricardi'
Subject: Re: [Megaco] Fax send/receive procedures


I would expect that the one operating Fax 2 would wait for an indication
that change to fax is desired. That would make the handshake in send
mode go through from Fax 1. 
 
The faxes follow ITU-T T.30, so you will find there the sequence for
V.21 Flags.
 
Gunnar


________________________________

	From: [email protected] [mailto:[email protected]]
On Behalf Of RUIKAR RAHUL A
	Sent: Mittwoch, 7. Januar 2009 04:44
	To: Andre Rosa Stefanini; [email protected]
	Cc: Alexandre de Brito Matricardi
	Subject: Re: [Megaco] Fax send/receive procedures
	
	
	Hi,
	 
	MG1 will also generate following event towards MGC.
	 -- > CNG
	 
	ctyp/dtone{dtt=cng}
	 
	For Reference check T.38
	 
	 
	 
	Regards,
	Rahul Ruikar
	Alcatel-Lucent
	Alcanet: 2721 4732
	 
	 

________________________________

	From: [email protected] [mailto:[email protected]]
On Behalf Of Andre Rosa Stefanini
	Sent: Tuesday, January 06, 2009 11:33 PM
	To: [email protected]
	Cc: Alexandre de Brito Matricardi
	Subject: [Megaco] Fax send/receive procedures
	
	

	People,

	 

	Could you help us in solving a question?

	 

	The scenario is the following:

	 

	Side A - Fax machine 1 -----> MG1 -----> MGC -----> MG2 ----->
Side B - Fax Machine 2

	 

	We are testing with 2 MGs controlled by an MGC via H.248 text
(according H.248.2)

	 

	First, the common voice call is setup by one side, not mattering
if A or B.

	 

	After that, let's suppose Fax Machine 1 initializes a fax
sending, pressing Snd/Rcv button. As soon as this occur, Fax Machine 2
presses Snd/Rcv button.

	Then, both MGs are reporting V.21Flag to MGC. Is it correct? 

	 

	Is there any possibility to distinguish which of fax machines
are sending the fax and which is receiving it? This is for avoiding the
other side (fax receiving side - Fax Machine 2) to send V.21Flag toward
the MGC.

	 

	It's not clear on IETF H.248.2 document whether is correct or
not both sides sending V.21flag toward MGC. Could you please clarify
this?

	 

	Thanks for your attention,

	ANDRE

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