As already stated, there are many variables that can affect modem connect speeds, but with a good quality (BT) line, and a decent external 56k serial modem (IMHO much better than internal) - you should achieve between 40,000 to 52,000 bps, but typically say 45,333 bps. These figures are only an initial connect speed, are mass variable, and the modem 'retrains' whilst in use.
You could try connecting via one or two different ISPs, to see if the speeds are any different.
If you never get better than 31,200 bps, then it is also possible that your line has been 'DACSed'(digitally split), to enable a near neighbour to have another line.
[ 08 December 2001: Message edited by: spekesoftly ]