We have an HP All-In -One. We can FAX “wirelessly” from the laptop using the printer, but our printer is hooked up to a “phone line”. But the “phone line” is actually a “Google number” that we pay nothing for that uses an Obihai network adapter. So essentially we are accomplishing what your friend describes because we have no landline coming to our house.
obi-talk? obihai is a semi curmudgeonly freeper
I have a brother all-in-one, but pretty sure HP printers work the same. To receive or print, my phone app handles the interim processing and sends the fax/print job to the printer through Brother's internet services to my printer located inside my local network. The printer needs access to the WWW through the WIFI router however.
Bkmk wireless fax
Can you send and receive using the google phone number?