I have HP Officejet Pro L7780 All in one . On the little screen it reads "phone off hook" I have a seperate line for fax. Cand anyone help?So what you are saying is that you are trying to PRINT, but that little screen pops up whenever you click "print"?

You need to go to your control panel, then to Printers and Faxes. Find the printer you want to use, and right-click it. Then click Set As Default.No that is not the ISSUE. I can print, but cannot fax. On the little screen on my printer it reads at all times "phone off hook." I am not aware of any changes being made. I have a seperate line for my fax line and all SEEMS normal and customary.
Thanks Could just be a phone line issue...check the phone line(s) connected to your all-in-one. If necessary, if this line runs to more than one location in the house...see if that line is in use or ANOTHER phone is off the hook.

You can also TRY removing the line from the wall jack and then plug it back in. You can also unplug the all-in-one and turn it back on again.No that is not the issue either. I have tried all of those things. Thank you for your suggerstions.