PW> I wonder why they didn't go upto 33.6Kbps earlier???

 JP> Simple: the technology which allows us to 
 JP> reach 33600 bps over PSTN
 JP> telephone lines didn't exist when V.34 was 
 JP> ratified by the ITU-T in 1994

 PW> What technology is that?

 JP> The technology which allows us to reach 33600 bps 
 JP> over PSTN telephone lines.
 
31200 and 33600 bps are possible by using the larger 1664  point constellation.
 
Previously V.34 had a 960 point constellation.
 
I believe that this also accounts for the increase in line rates people get
with lower rates under V.34(96) on bad lines.
 
Ludi.
ludi{at}triode.net.au

--- Maximus 3.01