sip

This article is based on the original that can be found here: http://row5.net/post/18655850352/cisco-ip-phone-7945-with-sip-configuration

This HOWTO assumes that your FreePBX system is sitting behind a NATed firewall with no direct connection to the outside world and it is NOT in the DMZ zone. If you are relying on this article to set-up your system, DO NOT place your system on a public IP address or a DMZ zone. This article does not address the potential security implications involved in such a setup.

The four key considerations in setting up remote extensions are:

Note 1: This guide has been tested with firmware version 3.3.1 and Bootrom 4.3.0. Be aware that different firmware revisions may have different web interface formats and functionality.

Note 2: This FAQ is based on a new phone OR one that has been reset to factory defaults. If in doubt, reset the phone to Factory Defaults.

The preferred method to configure a Polycom Phone is via Provisioning. You can however follow this guide to manually configure your phone.

Configuring the Phone to Register with 3CX Phone System