Ordinary serial and parallel devices require a separate power supply system, while USB devices do not. Because the USB connector linterface provides a built-in power supply. The USB power supply provides 5 volts of power to low-voltage devices, so new devices do not require dedicated AC power, reducing the cost and cost-effectiveness of these devices.
USB provides two-way data support for the phone. USB supports asynchronous and isochronous data transfer, allowing phones to integrate with PCs, share voice mail and other features. USB also features high-fidelity audio, which reduces the chances of electronic noise interfering with sound quality as USB audio information is generated outside the computer, giving the audio system greater fidelity.