[asterisk-users] T38 fax detection using g729

[Kevin P. Fleming]

On 04/20/2011 04:55 AM, Niccolò Belli wrote:
> Il 19/04/2011 23:41, Kevin P. Fleming ha scritto:
>> If you are the receiver of the call (and thus they are the sender of the
>> call), it is *your* system's responsibility to initiate the switch to
>> T.38, not theirs.
>
> Are you sure? So what's faxdetect=t38 for?

"Be strict in what you send, and liberal in what you accept."

It's there to compensate for calling endpoints that *do* initiate the 
switch to T.38 even though that's not the recommended behavior.

And after spending a couple of years working on T.38, yes, I am sure. It 
is the receiver's responsibility to switch to T.38 because only the 
receiver can determine whether a FAX terminal has answered the call. If 
the sender switches to T.38 based on CNG detection, the session could 
switch to T.38 when it was answered by a person, or even before the call 
has been answered.

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
Jabber: kfleming at digium.com | SIP: kpfleming at digium.com | Skype: kpfleming
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
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