A vehicle communication system is disclosed, which includes a voice output device for voice output, a voice pick-up device for voice input, a packet assembler/disassembler unit adapted for assembling different vehicle supplementary system data into respective packet data or disassembling demodulated packet data into corresponding vehicle supplementary system data, a GSM module adapted for transmitting data-carrying voice signal to a remote side or receiving data-carrying voice signal from a remote side, a carrier wave modulator circuit adapted for modulating packet data into analog signal and adding the modulated analog signal to the voice signal from the voice pick-up device to form a data-carrying voice signal for transmitting to a remote side through the GSM module, and a demodulator circuit adapted for demodulating data-carrying voice signal and discriminating the signal into packet data and voice signal.