Well, I got back to the Dreamcast dial-up project. I verified I had everything set up and did another test call from a handset to the number I configured and yep, I'm hearing modem noises.
I tried connecting from the Dreamcast and I got "NO CARRIER" multiple times, then after a few tries the text output box started speaking in tongues. I don't know enough about the USB modem I ordered to see what it's seeing, either. I'm stumped.

