Modem To Modem Networking in Windows98

Make both computers members of the same Workgroup. Manually assign IP addressed to the TCP/IP stack that is bound to the Dial-up Adapter on both computers that are in the same subnet (for example, on PC #1, use 192.168.0.1, and on PC #2, use 192.168.0.2, and on both PCs, use 255.255.255.0 for the subnet mask address). Make sure the Client for Microsoft Networks is installed on both computers. Set the Access Control level on both computer to "Share Level", and install File & Printer Sharing Services for Microsoft Networks. Configure the modem installed on the computer that you want to be the "server" to auto-answer when a ring is detected. Then, on the "server" PC, install Dial-up Networking Server, and install Dial-up Networking on the "client" PC.

You can find very detailed instructions in the MS-Knowledgebase article Q139710, which can be found here:

http://support.microsoft.com/support/kb/articles/Q139/7/10.asp?LN=EN-US&SD=gn&FR=0