Brian,
The problem with using "image" is that it would mean that a gateway would
have to do one of:
1) Close the audio session and open an image session
2) Open a second "image" session during mid-call
3) Open both an audio session and image session at the outset
For a lot of reasons, none of those options are preferred. In the latter
case, gateways just waste memory and CPU resources servicing sockets that
are never used. In the first two cases, there is a lot of extra signaling
on the wire. (For SIP networks, and especially IMS-based SIP networks, this
is horrible due to the widespread use of UDP, slow timer expiration, and
multiple hops through many proxies. Use of UDP and moderate packet loss, or
even TCP with light packet loss and several proxy hops, could cause a fax
call to fail due to timer expiration.)
What was preferred, instead, is detecting the fax tone and then sending a
payload type that is recognized as "fax" as negotiated during the initial
offer/answer exchange.
Paul
-----Original Message-----
From: Brian E Carpenter [mailto:brc(_at_)zurich(_dot_)ibm(_dot_)com]
Sent: Monday, August 14, 2006 2:57 AM
To: Eliot Lear
Cc: Paul E. Jones; dcrocker(_at_)bbiw(_dot_)net; ietf(_at_)ietf(_dot_)org
Subject: Re: RFC 4612 - historic status
Eliot Lear wrote:
Paul E. Jones wrote:
I wonder how customers might react to seeing new gateway hardware
produced
utilizing "historic" RFCs. What does that mean?
It means that one standards body has decided to cite a specification
that has been deprecated by another.
It would have been better, imho, if ITU had decided to cite the non-
deprecated
image/* MIME types, but that is not a decision the IETF can control.
Brian
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