It has to be hooked up to your computer. With the program running, it would use the modem in your computer to answer the fax and print it out. If you don't have your computer on and the phone line pluged in, it won't work. Thats why I got the 960, it has a built in modem.

What program needs to run?

When you installed the printer, it should be in there. I am sorry I can't be of much help in this matter. It's been a while since I even used my computer to recieve or send faxes. But if you start up the Dell A920 control center, it should have an icon in the start tray below. It should help you there, or maybe inside the manual.

try the program called FaxTools I Have used it several times and it works great