1. You need to download the driver for Ricoh Afficio C2500 from the Ricoh support site, here.
2. Run the "z59592en.exe" file to unpack its contents.
3. In the folder where you unpacked the driver (by default it is c:\temp\z59592en\DISK1\) locate the "printer.inf" file and edit it as showed bellow:
4. Install the Lan Fax Printer as you would do normally ("Add printer" from the "Devices and printers" windows).
In Windows 8 you will have to disable driver signature enforcement.