I know some older space stations had fax machine (since Sayult 7 at least). Do they still have it on the ISS ?
Does is support in/out or only one way communications ?
The ISS does not have a fax machine. There are two Epson 800 inkjet printers onboard connected to the ISS local area network. Any document sent up from the ground that the crew needs to print, can be printed on this printer.
Next year, the aging Epson 800s are planned to be replaced with a new HP Envy, specially modified for free-fall.