Inspection Procedure 1: Hands free cellular phone system does not work normally: Function

During the conversation with the hands free cellular phone system, the signal of speaker's voice is transmitted from the microphone unit to the hands free module. Then the signal is transmitted from the hands free module to the cellular phone. The voice of other party is transmitted from the cellular phone to the hands-free module. Then, the voice is transmitted from the hands free module to the radio and CD player <vehicles without MMCS> or audio visual navigation unit <vehicles with MMCS>, and output from the speaker.