Abstract: A method of reducing media relay of a network address translation (NAT) apparatus involves detecting a network type of a user agent (such as a network address port translator) to determine whether the user agent is a symmetric network type; if it is, a transmitting server is still required to relay a media stream; if it is not, a SIP standard structure and its communication protocol are utilized for changing a network address and its connecting port of an ‘invite’ packet via a proxy server so that the caller and the callee will send the media stream according to the changed network address and its connecting port.