1. Boeing is the designer and assembler of all Boeing aircrafts. It also subjects the new aircrafts to rigorous test. It is totally responsible for the certification of the aircrafts and all the parts, avionics and safety features of the aircrafts.
2. The parts may be supplied by contractors and vendors but Boeing is responsible for the correct installation, testing and certification. Certainly the communication system is selected, tested and installed under Boeing supervision.
3. The communication system is the lifeline of the aircrafts. In any emergency the aircraft can speak directly with ground stations. Under no circumstances should communication equipment fail.