If an IP phone disconnects frequently, drops calls mid-conversation, and disconnects again a while after a restart, troubleshoot following the steps below:
Step 1: Check network stability. Frequent disconnections are most likely caused by network fluctuations. Connect a computer to the same network segment as the IP phone, then ping the gateway and registration server to check for packet loss or excessively high latency. If the ping values fluctuate drastically, first check if the switch port is loose, then see if there is interference from high-power devices nearby—such as microwaves and routers, which may disrupt the network signal and cause the phone to disconnect.
Step 2: Verify stable terminal power supply. Most IP phones use PoE power supply. Insufficient power of the PoE switch or unstable power supply due to aging network cables can cause the terminal to restart and disconnect frequently. Replace the cable with a compliant one, or power the phone with an independent power adapter, then observe for half a day. If no disconnections occur, the issue lies with the power supply.
Step 3: Check device firmware and server load. If the network and power supply are normal, check if the IP phone is running an outdated firmware version—old firmware may have compatibility bugs, so download and install the latest firmware from the official website and try upgrading. Contact the operation and maintenance team to confirm if the registration server is overloaded; a large number of terminals connecting to the server at the same time can also cause frequent disconnections of some devices.
If the phone still disconnects after all the above checks, the problem may lie in the network topology, such as routing configuration conflicts on layer 3 switches.