Secure quantum telephone

A quantum telephone protocol including the dialing process and the talking one is proposed. In the dialing process, with their respective secret keys, the legitimate communicators Alice and Bob can pass the authentication by Charlie acting as a telephone company. In the talking process, Charlie provides the authenticated Alice and Bob with a quantum channel sequence, on which Alice and Bob can communicate with each other directly and privately by virtue of some encoding operations. Different from the insecure classical telephone having been used in our lives, the proposed quantum telephone protocol has asymptotically security and the communicators cannot disavow having used the quantum channels.