I can't fax with XP

I had the fax set up in XP and it worked great. But I had to uninstall and
then reinstall XP. Now I can't get the fax to work. I wanted to set it up
like before when a call came in a bubble would pop up in the Systray and ask
if I want to answer the call as a fax. I've got the phone line plugged into
"line". I went through the set up wizard and configured the fax. I also have
SP2 installed, but I had it installed last time too. Thanks.