The Pantech PX-500 is a mobile broadband PCMCIA card used by Sprint so
I think that's what's meant by 'dial-up' in this sense. It's not the
old dial-up that we all used to have to work with As for why it
doesn't work in the KDE desktop I suspect that there's parts of the
KDE system missing from the install and that's why the original one
works ?

I did read somewhere that the phone number expected is 00000000 so
that might the the answer ?

BTW - there are still some poor unfortunates who cannot get anything
other than the old dial-up system over the phone lines because the
alternatives either are too expensive ( e.g. satellite ) or they
aren't covered by those services even if they could afford it.