(recommended for PowerMacs)
Open Transport is the newest Macintosh technology for connecting to the internet. It's typically faster on PowerMacs than the older MacTCP.
If you're not using a PowerMac, you're probably better off sticking with MacTCP unless you have at least 16MB of RAM. If you are daring or hardheaded enough to want to use the latest and greatest anyway, here are Apple's system requirements for using Open Transport:
For dial up internet use, you will need both Open Transport and Open Transport PPP.
The latest version of Open Transport is v1.2, available only with Mac OS 8 at this time. The latest version you can download is v1.1.2.
The only version of Open Transport PPP available to download is v1.0.
If you're a MacAddict subscriber, you can find both on CD number 7.
Install Open Transport first, then install Open Transport PPP.
If you have both Open Transport and Open Transport PPP on your system, you'll have the following three control panels: TCP/IP, Modem, and PPP. (If you do not have these items, see "What do I need?" above.)
Open the Modem control panel. Here's what the Modem window looks like:

Close the Modem window. Click Save when asked if you want to save the changes.
Open the TCP/IP control panel. The finished version will look something like this:

Close the TCP/IP window. Click Save when asked if you want to save the changes.
Open the PPP control panel.

Now, click on the Options... button at the bottom. Choose the Connection tab as shown below:

Uncheck the top option, Connect automatically when starting TCP/IP applications, if desired. If left checked, this option attempts a connection every time your computer is turned on, as well as any time a browser or mail program is opened. Although some prefer it that way, it sometimes fails future connection attempts after the first successful connection.
Open the PPP control panel. Click Connect. Wait for the Send and Receive bars to appear in the window:

You're connected! Enjoy the ride.
For easier access, make an alias of the PPP control panel and put it on your desktop.
Be sure to check for the latest Apple software updates.