On Sat 14 Dec at 15:09 Mark Griffiths (3:640/305) wrote to Arthur Marsh:

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

Yes, and the signal-to-total distortion ratio plummets if you over-equalise.

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

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

What data signalling rates?

--- msgedsq 2.1