I was an intern at IBM working on their Mwave DSP modem team. For about a year my job was to dial up different BBS systems and see which ones we could connect to and which ones we had trouble with, so I listened to a lot of modems. After awhile I wrote a Visual BASIC program to do the work for me. It was a pretty interesting job, actually. I actually called the AOL data center in Virginia to ask which modem brand they used because we had a bit of a hard time connecting reliably.