Question

Can you use or connect a smartphone in a fax machine? Is there an an app for that if I want to do that?

Answer 1

If there are both connected in the same network, it`s likely not to need an app

For example your smartphone is turned on Bluetooth mode and has identified the fax nearby, press Next similarly to any device that you want to link to it

I`m not very sure about the other brands of fax, but I know that Panasonic developed an Android app for this situation