Cockpit,

For starters the headset one is more than likely a simple
analog input whereas the flightcell is fully microprocessor controlled - has
built in intercom - satelite input/output - individual gain control on all
channels - interferance rejection etc.


Which gives you exactly what in added functionality with regard to the OP's
request, namely using a cell phone in flight?

--
Thomas Borchert (EDDH)