-=> Quoting Arthur Marsh to All <=-

 AM> As you can imagine, the 3429 symbol rate of V.34 requires 
 AM> about 3429 Hz of bandwidth to the 3 dB points, therefore 
 AM> with a low frequency cut-off of 244 Hz and a centre 
 AM> frequency of 1950 Hz, one needs a high frequency cut-off of 
 AM> 3672 Hz, which is higher than the 3400 Hz 3 dB cut-off of 
 AM> S12-S12 connections and still higher than the 3500 Hz 3 dB 
 AM> cut-off of AXE-AXE connections.

Have you heard of equalization?  Equalizers allow you to go beyond the 3dB
cutoff points by modifying the transfer function of the channel so that the
equalized channel has a more linear performance.  The high frequency 
response of a phone line is limited by the low pass filters before and
after digitization.

 AM> The V.34 probe tones of 3450 Hz and 3600 Hz some-how have 
 AM> to figure out the high frequency roll-off of such a 
 AM> connection...

According to Telstra, I'm on an S-12 exchange, and I almost invariably get
3429 symbol rates on my connections using a Courier.

Regards,
Mark Griffiths.

... "We are upping our standards... so up yours."
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