Usman,
Did you download the drivers and install them? If not, you can get them from here:
http://www.physcip.uni-stuttgart.de.../redhat/8.26a9/
These are all rpm's for redhat.
The last time I installed the lucent drivers, it did not create a link from /dev/modem to /dev/ttyLT0. So keep that in mind. Also I prefered to use kppp to start the ppp daemon. It is very similar to windows world, and also can do time accounting if you want. Also if you use KDE, it has a nice applet that can dock into kicker.
If the rpm errors out, post the results and we can go from there.
Cheers