Problem with Internet Connect


I'm having a problem with internet connect. Everytime I go to connect to the internet, an error window is displayed that states the server is busy, or the line is busy. Calling the number manually through my phone I can hear the typical modem sounds as the two computers send each other to connect. Connecting to the internet in Mac OS 9.1 is obviously not a problem, otherwise I would not be able to post this message. This has happened before in Mac OS 9 (and previous versions) and solution was to delete TCP/IP preferences and retype all the IP address information into the appropriate fields of that control panel. Is this a similar situation with Mac OS X? Which file(s) do I delete? I have no idea how this happened, there was no apparent system crash.

Blue & White Power Mac G3, 400MHz, 640MB RAM
12GB Ultra ATA66 HD, 18GB UltraSCSI HD, 100MB ZIP,