Um, not sure if this helps much, but the specific prohibition on cell phones specifically is from the FCC, not the FAA. Look it up in Title 47 Part 22.925 of the Code of Federal Regulations. The FAA's regulations (unless I am misinterpreting the CFRs which, as I AM NOT A LAWYER NOR A LEGAL AUTHORITY OF ANY TYPE WHATSOEVER is possible) seem to deal with portable electronic devices in general in Title 14 Part 91.21.