They are listed in the order of simplicity. Telnet This is very simple, but the only functionality you get is that you can log in to the modem pool server, called annex. When logged in there, you can log in remotely with telnet to other hosts on the net. You quit the annex with the command hangup . The only program you need is a terminal emulation program that can communicate with your modem.
Most computers have such a programs among the standard programs delivered with the operative system.
What you need is a PPP-client and there are many freely or almost freely available on the net. You need to install the client and configure it for use with your modem and the modem pool server. This is a Macintosh only protocol used to give a Macintosh view of the network. To use ARA you need an ARA-client on your Macintosh. The things you need to configure is your modem and the accompanying CCL Script.