Come to think, I've got a couple ISA modems in a parts box somewhere that are FAX capable. While cell phones suck for audio quality, 4G LTE HD and VOLTE might have enough and consistent audio quality to support slow FAXing. I've read about people trying and failing with previous versions. I've had some ideas about maybe interfacing an old modem chip to a headset interface and maybe get that working. I don't FAX often, but most of my doctors still use it. I sure as hell don't trust the free online FAXing services with my medical records.