Comment by jandrese

IIRC connecting to the PSTN the best you would ever see was 48kbps, at least in the states, although if you were transferring uncompressed data in the clear sometimes the modem could compress it for you on the fly to get more data on the wire. In practice though big files tended to be compressed already so you rarely saw much benefit from that. You needed some sort of closed phone network that didn't compress the voice channel the way the phone company did in order for the modems to negotiate up to the max.