What step should be performed first to troubleshoot a Local IP Phone that loses registration to 3CX?

Beginning with a Wireshark capture on the 3CX Server is an effective first step in troubleshooting the issue of a Local IP Phone losing registration. Capturing network packets allows you to analyze the communication between the IP phone and the 3CX system, helping to identify where in the communication process the issue may be occurring. By examining the capture, you can see if the registration requests are reaching the server, whether responses are being sent back to the phone, and if there are any errors or disconnections happening in transit.

This method provides a detailed view of the traffic, enabling you to diagnose problems such as misconfigured network settings, firewall issues, or even underlying connectivity problems that may not be immediately apparent through other troubleshooting steps. Once you gather this data, you can take targeted actions based on the specific issues observed in the capture, making it a foundational step in effective troubleshooting.

Checking network connections, rebooting the phone, or updating the firmware are all valid troubleshooting steps; however, they may not provide immediate insights into the root cause of the registration issue without first understanding what is happening on the network level. Starting with packet analysis allows for a more systematic approach to diagnosing the problem.