I recently dug out my old modem and in a fit of nostalgia thought I'd try using my otherwise neglected voice line to call some BBSes (yes, they still exist!). However, I've found that while I can connect to the other side and get the welcome banner from the remote system, I soon start to see random character "noise" flooding onto the screen.
I assume this is something to do with the VoIP connection being optimized for voice rather than data. Is there a way to put the connection into a data/fax mode when making the call? I've read that some VoIP providers give you a *NN prefix to dial first when you're sending faxes.