External Ethernet Modem no nic

I suppose this topic is not really related to the word group, but this is my
main discussion group.You all have macs and might be able to help.

I want to sign up with SBC in California. For my mac G3 Powerbook Wallstreet
not all of SBC's equipment is compatible. They have told me that I need an
"External Ethernet Modem no nic" which they don't have, don't know much
about, and don't know where I can get one.

I think it's a pcmcia card for the card port and on it's outside edge has a
female phone jack. It may also be the modem itself.

I'm not knowledgeable on ethernet or cards and a search on the web has not
found any answers or suppliers for me.

Any suggestions

Rafael