Apple PowerBook G3 - Manual (Page 143)

Connecting a telephone line to the expansion card
If your card provides both modem and Ethernet connections, follow these
steps to connect a standard telephone line to the card in your PowerBook:
1 With the PowerBook shut down, open the cover on the computer’s back panel and verify
that your computer has a card with a modular connector.
You can check the label on the inside of the cover to determine that the card
provides a modem.
2 Connect one end of a modular telephone cord that came with your computer to the wall
socket for a residential phone line.
3 Connect the other end of the telephone cord to the modular connector on the card.
Modular
connector
on card
Telephone connector
WARNING Make certain that the phone line is the standard (analog)
residential line, not a digital line. Connecting a digital line to your
modem card could damage it. Also, you must use a single-line
telephone cord (supplied with your computer) to connect to the
telephone line. A single-line phone cord has only two wires visible in
the plastic connector (as opposed to the commonly used four-wire cord).
2 visible wires
Single-line telephone cord
143 Making Modem and Ethernet Connections to an Internal Expansion Card