RE: [AVT] V.32 AA AC in RFC2833bis

["Yaakov Stein" <yaakov_s at rad.com>]

> Thanks.  Your remarks on frequency were helpful in confirming 
> my impression.  It looks like it would be a good idea to add 
> the events AA on the calling side and AC on the answering 
> side, with advice to transition into V.150.1 modem relay 

or clear channel (RFC 4040) when modem relay is not suported

> when these are detected.


BTW, there is another interesting trigger signal that is sometimes
still seen. For pre-1993 versions of T.30 fax, the calling station may
omit the CNG tone, and start with the V.21 flags. 
Once again, it doesn't make sense to send the individual bits 
using the V.21 event defined in 2833bisdata, 
rather one should detect the V.21 flags using an appropriate
spectral feature and transition to T.38 or T.37 or clear channel.


Y(J)S

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