I was told that the compression that cell phone companies use would only work for voice and not fax tones, and we can't use it for fax. At the time I was trying to find out why there is no app that would send fax over the cell phone line (not data). All it has to do is translate a bit map into fax tones and a smartphone should do that very easily as it is easily 100x more powerful than any chip inside a fax machine.