Paganini,
It would not be to hard to do. You would set up one modem to automatically answer. On the other side you instruct the modem to dial using AT commands. Once the connection has been established then you can use it as if it were a regular serial connection. The following tutorial describes how this can be done between a FP-2000 module and a host computer, but the idea would be the same between two computers.
http://zone.ni.com/devzone/conceptd.nsf/webmain/4B5DC1F4481A33F286256B4A007D0216?OpenDocument
Carl L
National Instruments
