Configuration of NAT-Traversal 31Modifying Proxy parametersAfter you have enabled either the LAN or WiFi connection profile and haveconfigured the settings to allow successful connection of the IP Phone 1535to your local network, you can configure the IP Phone 1535 to find and useyour installed proxy server in its operations with your installed MCS 5100.For successful registration of the IP Phone 1535, you must access andmodify the parameters of the Proxy configuration option as described below:Step Action1 From the Main Menu, select Settings > VoIP Settings > Proxy,and press OK.2 Select the parameters to modify by choosing the appropriateconfiguration options and pressing OK. Enter the values as required.The available configuration options are as follows:a. Proxy Address: Configure the Proxy server address information.b. Proxy Port: Configure the IP Phone 1535 to use a specific portto connect to the network proxy server. By default, the proxyport value is 5060.c. NAT/Timer (OPTIONAL): Modify the timing value used tomaintain network connectivity through a firewall. The timingoptions available are 30 seconds, 45 seconds, 1 minute, 1.5minutes, 2 minutes, 2.5 minutes, 3 minutes, and 5 minutes. Bydefault, this value is 2.5 minutes.NAT-Traversal: The IP Phone 1535 supports two methods of NATTraversal - the SIP-PING method and the • STUN method. For moreinformation on configuring NAT-Traversal, see "Configuration ofNAT-Traversal" (page 31).—End—Configuration of NAT-TraversalThis section provides a description of NAT-Traversal on the IP Phone 1535,and its subsequent configuration.The IP Phone 1535 supports two methods of NAT-Traversal:• SIP-PING: requires a Boarder Control Point (BCP) server for the MCS5100 Release 4.0 and a RTP Media Portal server for MCS 5100 Release3.5 if it is located behind a NAT/firewall.• STUN: The STUN protocol lets a client discover the presence and typeof NATs between the client and the public Internet - a STUN server canNortel Multimedia Communications Server 5100Nortel IP Phone 1535 Installation and CommissioningNN43160-300 00.13 PreliminaryRelease 4.0 22 August 2007Copyright © 2007, Nortel Networks.