The first time I configured Linux to work as a PPP client with an ISP, I found that there were lots of things to do.
Feedback is welcome.
This page is developed on Red Hat , but differences with Slackware should be covered. You first need to enable PPP support in your Linux kernel. Major distributions, like Red Hat, Slackware and Debian, have this enabled by default. If it is not enabled, you need to reconfigure and recompile your kernel. This is included with all distributions.