Abstract: A method of switching between a VoIP call and a traditional call, involving the use of a caller terminal, a call box device, a first computer device, a second computer device, and a receiver terminal. A VoIP connection has to be established before the caller terminal and the receiver terminal can engage in a VoIP call. If the VoIP connection is successfully established, a computer device electrically connected to the caller terminal monitors the Internet quality between the caller terminal and the receiver terminal. If the Internet quality is poor, upon the pressing of a predetermined key, the caller terminal alternatively connects to the receiver terminal via a PSTN call through the switching of the call box device, which is electrically connected to the receiver terminal.