Configuration of Network Address Translation (NAT) Support Parameters on the SPA2102 Objective Session Initiation Protocol (SIP) is a protocol that can be used to control voice and video sessions over IP. The NAT Support Parameters are different settings that can determine how SIP is used to interact with the SPA2102. The objective of this document is to explain how to configure SIP Network Address Translation (NAT) Support Parameters on the SPA2102. Applicable Devices • SPA2102 Step-by-Step Procedure NAT Support Parameters Step 1. Use the configuration utility to choose Advance > Voice > SIP. The SIP page opens. Step 2. Configure the parameters to your specifications. • Handle VIA received— From the drop down menu select yes or no. If yes is selected the SPA2102 locates the IP address in the "received=" location and this IP address is used as the public IP address for the SPA. • Handle VIA rport— From the drop down menu select yes or no. If yes is selected the SPA2102 locates the UDP port in the "rport=" location and this port number is used as the public UDP port. • Insert VIA received— From the drop down menu select yes or no. If yes is selected the SIP replies sent from the SPA2102 will add a "Via:" header that is the same as the IP address that came from the SIP request. • Insert VIA rport— From the drop down list select yes or no. If yes is selected then the SIP reply sent from the SPA2102 will add a "Via:" header that is the same public UDP port that came from the SIP request. • Substitute VIA addr— From the drop down list select yes or no. If yes is selected the public IP address and port discovered by STUN are used instead of IP address and Port that were being used by the SPA. • Send Resp to Src Port— From the drop down list select yes or no. If yes is selected the "Contact:" header will be ignored and a reply will be sent back to the IP address and port from where the SIP message came. • STUN Enable— From the drop down list select yes or no. If yes is selected the Simple Traversal of UDP through NAT Stun will be enabled. • STUN Test Enable— From the drop down list select yes or no. If yes is selected the SPA2102 will perform STUN tests. The result of the test will determine which type of NAT the SPA2102 is behind. The results will be displayed in the SIP headers of the REGISTER. The procedure will also influence other NAT-related features on the SPA2102. • STUN Server— Enter the STUN server that is to be used. (I.E. _stun._udp service, a hostname:port, or IPaddr:port) • TURN Sever— Enter the Turn server that is to be used. • Auth Server— Enter the Auth server that is to be used. • EXT IP— The public IP address that is used to replace the private IP addresses in the "Via:", "Contact:" and "c=" fields of the SDP. • EXT RTP Port Min— The port used for minimal RTP Audio to act as a replacement of the private UDP port found in "m=" of the SDP. • NAT Keep Alive Intvl— The maximum time (in seconds) that the pinhole in the NAT/firewall will be left open between two packets. Step 3. Click Submit All Changes to save your NAT Support Parameter settings. .