The FCC regulates cell phones, not the FAA. IIRC the FAA activity is dealing with pretty much everything except cell phones.
The FAA regulates all airborne electronic devices. The rule for that hasn't changed in the thirty years I've been flying. There's been some "non-regulatory" guidance that the FAA has given the carriers over the years as far as how to interpret the reg, and that in fact is all that's really on the table now.
The only FCC reg on cellphones in aircraft is also by and large obsolete. It covers only those services licensed under Part 22 subpart H the original analog (AMPS) cell phone rule. Stuff licensed under PCS or other services (while it quacks like a cell phone) aren't subject to that section and no other section has any prohibition on airborne use. The main impeteus on that by the way is not that it has any bearing on the aircraft but it messed up the old analog cell system royally. The rule was pretty much lost on the common man. The only real mandate it had was that cell phones installed in aircraft had the "not to be used in the air" placard put on them.