If your IP phone suffers from frequent disconnections, sudden call drops, or temporary recovery followed by re-disconnection after a restart, you can troubleshoot step by step in the order of network → power supply → device/server → network topology. The detailed procedures and recommendations are as follows:
Step 1: Check Network Stability (Most Common Cause)
Core Objective: Verify if there is packet loss, excessively high latency, severe fluctuations, physical link faults, or interference issues.
- Ping Test Verification
- Operation: Connect a computer to the same network segment as the IP phone and execute the ping command:
- Ping the gateway IP (e.g.,
ping 192.168.1.1 -t; use-tfor continuous ping on Windows; use-c 60for 60 continuous pings on Linux/macOS). - Ping the registration server address of the IP phone (SIP server, e.g.,
ping sip.xxx.com -t).
- Ping the gateway IP (e.g.,
- Judgment Criteria: A packet loss rate > 1%, latency > 100ms with large fluctuations (jitter > 30ms) indicates network problems.
- Operation: Connect a computer to the same network segment as the IP phone and execute the ping command:
- Physical Link and Interference Troubleshooting
- Check switch ports and network cables: Re-plug the network cable, switch to another switch port to see if there is any looseness; use a cable tester to check if all 8 cores of the network cable are connected (8 cores are required for IP phones/POE).
- Eliminate electromagnetic interference: Keep the IP phone away from microwave ovens, high-power routers, wireless APs, frequency converters and other devices to avoid network signal interference caused by 2.4G/5G signals or electromagnetic waves.
- Temporarily rule out WiFi interference: Prioritize wired connection for the IP phone, turn off the WiFi on the same network segment, and observe if the problem is resolved.
Step 2: Check Terminal Power Supply Stability (Common in POE Scenarios)
Core Objective: Verify if the POE power supply capacity, network cable voltage drop, or power source is normal.
- POE Power Supply Troubleshooting
- Confirm POE switch specifications: The power consumption of an IP phone is generally 5–15W. Use a POE switch compliant with the 802.3af/at standard to avoid unstable power supply caused by non-standard or underpowered devices.
- Replace with a compliant network cable: Use CAT5e or higher-grade network cables (wire diameter ≥ 0.5mm). The recommended POE power supply distance is ≤ 100 meters to prevent excessive voltage drop due to long cable lengths.
- Temporarily switch the power supply method: Use the dedicated power adapter (matching voltage and current) of the IP phone for power supply, and observe for half a day. If disconnections no longer occur, the root cause is confirmed to be the POE power supply.
Step 3: Check Device Firmware and Server Load
Core Objective: Rule out terminal firmware bugs, configuration errors, or registration server overload/failure.
- Firmware Upgrade
- Operation: Log in to the web management interface of the IP phone, check the current firmware version, and download the latest firmware from the official website for upgrade. Outdated firmware may have compatibility bugs that cause disconnection issues.
- Registration Server Load Verification
- Contact the operation and maintenance team to confirm if the registration server is overloaded. If a large number of terminals connect to the server simultaneously during peak hours, it may cause frequent disconnections of some devices.