The present invention provides a communicating device and a method for peer to peer communication between voice over IP (VOIP) devices by means of transmitting IP address to remote site by Call ID method and establishing a data structure. The data structure stated above may record the Internet IP address corresponding to the outgoing and incoming VOIP phone number. When a user dials or receives the phone number recorded in the data structure, the communicating device with this data structure will find the Internet IP address corresponding to this VOIP phone number and using this IP address for peer to peer communication. It is unnecessary to register to SIP proxy or Call Agent which provided by service provider.