Can't receive Fax from one party

[meg-c]

HP Officejet 8620, can send and receive faxes from everybody except from one telephone number.  Has this number been blocked? and how do I unblock this numbers?

[A4Apollo]

Hi! @meg-c, Welcome to HP forums.

I understand you have issues receiving fax from one party.

Don't worry I'd love to help you out.

Did you make any changes to your printer?

Are you able to send a fax to that particular number?

Please try the steps recommended below.

Turn the printer on, if it is not already on.
Wait until the printer is idle and silent before you continue.
With the printer turned on, disconnect the power cord from the rear of the printer.
Unplug the power cord from the wall outlet.
Wait at least 60 seconds.
Plug the power cord back into the wall outlet.
   NOTE:
HP recommends connecting the printer power cord directly to the wall outlet.
Reconnect the power cord to the rear of the printer.
Turn on the printer, if it does not automatically turn on.
The printer might go through a warm-up period. The printer lights might flash, and the carriage might move.
Wait until the warm-up period finishes and your printer is idle and silent before you proceed.

Refer this article to further troubleshoot cannot Send or Receive Faxes.

I'll keep an eye out for your response.  

I hope you have a great day! 🙂