modify four lines in the file /etc/ppp/ppp.conf.

You will find the following lines at the end of /etc/ppp/ppp.conf:

papchap:

#
# edit the next three lines and replace the items in caps with
# the values which have been assigned by your ISP:
#

set phone PHONE_NUM
set authname USERNAME
set authkey PASSWORD

Assuming your ISP name is MYISP, your phone # is 123-1212, your username is USER and your password is PASS, you would do the following:

MYISP:

set phone 555-1212
set authname USER
set authkey PASS

Save your changes and from the command line do this:

# ppp -auto MYISP

Now ping an IP or access your network. Your modem should dial your ISP and connect. That's all there is to it.

Note that this assumes your modem is on com1. If not, tweak the beginning of your ppp.conf file under the default: section.