One other possibility for such problems is a mismatch in the MTU size. In theory the MTUs should negotiate to a common size. We have also encountered a few modems of very recent manufacture that do not like the command characters to be sent at computer speeds. You can override the normal speed by adding a PACE command to your script. A few modems will also not accept other command, including the dial command, for the same reason.
Most folks manage to install and configure their MacSLIP in a few minutes.
Some service providers use an interface that is more complex, and configuration of MacSLIP will take a little longer. Hopefully, if you run into a problem, these notes will help. Back to the Hyde Park Software home page.