From the control panel, navigate to:
Settings > Fax > Analog Fax Setup > Fax Receive Settings > Admin Controls
For non-touch-screen printer models, press to navigate through the settings.
Set Block No Name Fax to On.
Learn how to delay the printing of received fax messages.
If you experience failure in getting incoming faxes, then make sure that the trays and the toner cartridge are not empty.