Apparatus and method for supporting nat traversal in voice over internet protocol system

A method for operating an exchange for supporting Network Address Translation (NAT) traversal in a Voice over Internal Protocol (VoIP) system, the method comprising:

• receiving media data from a calling Internet phone based on a first source address and a first User Datagram Protocol (UDP) port information, and a first destination address and a second UDP port information;
• determining a second destination address and a third UDP port corresponding to the first destination address and the second UDP port, and a second source address and a fourth UDP port corresponding to the first source address and the first UDP port using a mapping table;
• and
• relaying the media data to a called Internet phone based on the second destination address and the third UDP port, and the second source address and the fourth UDP port.

A method for operating an exchange for supporting Network Address Translation (NAT) traversal in a Voice over Internal Protocol (VoIP) system, the method comprising:

• receiving a packet from an Internet phone;
• comparing an IP address and a User Datagram Protocol (UDP) port of the received packet with registered information;
• converting the IP address and the UDP port of the received packet into an IP address and an UDP port for the NAT traversal;
• and
• relaying the received packet to a counterpart Internet phone using the converted IP address and UDP port.

A system for supporting Network Address Translation (NAT) traversal in a Voice over Internal Protocol (VoIP) system, the system comprising:

• a calling Internet phone for transmitting a setup request signal to an exchange to receive IP address and User Datagram Protocol (UDP) port information for NAT traversal of a called Internet phone;
• the called Internet phone for transmitting a response signal to the exchange in response to the setup request signal to receive IP address and UDP port information for NAT traversal of the calling Internet phone;
• and
• the exchange for generating an IP address and an UDP port for NAT traversal of the called Internet phone, for relaying the same to the calling Internet phone, for generating an IP address and an UDP port for NAT traversal of the calling Internet phone, and for relaying the same to the called Internet phone.