TTD/TTY devices use normal phone lines to communicate. An individual with a TTY/TDD can either communicate with another TTY/TDD device or can make a call to a standard telephone. In this case, the TTY/TDD device calls a live relay operator and the live relay operator communicates with both parties either with a TTY/TDD device or uses their normal human voice on a standard telephone. It is important to note that there are different protocols that can be used to communicate with TTY/TDD devices, however many newer TTY/TDD devices can handle a wide range of protocols and can even communicate directly from a personal computer using special software and a computer modem.