modem on unix

We have a sco-unix system v rel 5.02 installation. We need to know how to install a US robotics 56k faxmodem with personal voice mail so as to connect the system to the internet. we have followed the installation procedure mentioned in the “sco unixinstallation of modem ” documentation. on issuing the command “cu -ltty1a dir” the system makes a beep sound and them displays disconnected. we need to know the full installation procedure for the mentioned modem.
Srivas
biz@networldvirtual.com
kaink@yahoo.com