The credit card mobile phones now provided on some aircraft, do not interfere with aircraft systems because they are wired to a special "base station" that has been designed to safely receive and transmit radio signals in the aircraft.
Credit card mobile phones have good sound quality
( z1 quality :mod ( z2 sound ) :ARG1-of ( z3 good ) :domain ( z4 phone :ARG1-of ( z5 mobile ) :instrument ( z6 card :mod ( z7 credit ) ) ) )