If its PCMCIA with serial cable. You can use wvdial as the dialer.
>>> Download wvdial.rpm <<<

Configure it as follows. Type or copy and paste the text given below, to /etc/wvdial.conf
Code:
[Modem0]
Modem=/dev/ttyS0
Baud=115200
SetVolume=0
Dial Command = ATDT
init1=ATZ
init2=AT+CRM=1
FlowControl= Hardware (CRTSCTS)
[Dialer tata]
Username= internet
Password= internet
Phone=#777
Stupid Mode= 1
Inherits = Modem0