I'm trying to do something similar and am struggling !

I have a bunch of dataloggers at remote locations with gsm modems. On
the PC at base I have standard analogue modem on a BT line, which I
use to download data and manage the loggers. I want to discard the BT
line and to see if I can do this operation via VOIP or another
internet based process. Download speed only needs to be 9600 (the max
speed for the GSM modems).

There are useful articles on the principles at http://www.modemsite.com/56k/voip.asp
& http://www.voip-info.org/wiki/index....%20over%20VOIP but
I have no found any info on a practical "how to" solution. The
problems seem to be to do with the compression codecs used in VOIP
being designed for voice and not data - surely there is a software
solution somewhere ???

Any ideas/help would be appreciated