Getting the most out of your USR Sportster in Debian

Larry asks: "I've got a USR Sportster 56K INT modem, jumpered to be COM2. Under Windows it gets 50,667cps, but only 31-33,600cps when I'm using Debian. What is the correct script to achieve faster downloads in Linux? The default script is 'ATZ'" Ah, the days of the AT command set...however I've never seen a modem with well configured factory defaults. Any suggestions?