Go to the "logitech driving force problem" thread, there is a link about a guy who found a fix for it and the link mentioned the Radioshack part number.
Repeat after me: This is NOT a standard phone plug.
It is a little smaller. If my memory is correct, that the kind of plug DEC computers used for their keyboards. That plug is also used in some light headset ( switchbords and transcription equipment ).
Just for the fun, try to connect your driving force pedals to ... your phone line, you'll see that the jack and plug don't match.