Hi,
you can use the PCtel HSP56 AMR and others modems devices which didn't work with pctel-0.9.6 (or other) driver. Download the file slmodem-2.9.6.tar.gz on ftp://ftp.smlink.com/linux/unsupported and follow the instructions in README file. It's easy to install, and I got to do it works with the slackware 9.1 and kernel 2.6.5. So, I hope that you too.