Unfortunately you do have to configure kppp too.
You have to enter set up, select your modem and enter your isp,
name, phone# and anything else it needs to work.
There is a place to query modem too and that's key
because if it can't find the modem after you've completed the
kppp modem info then something is wrong.

Some people here don't like kppp.
You can also try ( at a terminal ) "pon the_account_you _created"
if that works "poff" will close the connection. Good luck

As a last resort you could also look at minicom type "man minicom"
at a terminal to check it out.