Check Physical Connections

• Power: Ensure the phone is plugged into a power outlet or powered through PoE (Power over Ethernet).
   
• Ethernet: Verify that the Ethernet cable is securely connected to the LAN port of the phone and to the network switch/router.
   
• Headset/Handset: Confirm the handset/headset cables are properly plugged in.

Verify Network Connectivity

• Network Link Light: Check for blinking green/orange lights on the Ethernet port.
• Internet Access: Ensure your network has internet connectivity.
• Router/Switch: Restart the router or switch to refresh the network.

Reboot the Phone

• Press the Menu button > Select Reboot (or unplug the power cable and plug it back in).
   
• Allow the phone to restart and reconnect to the network.

Check for Firmware Updates

• Go to Menu > Status > System Info to check the firmware version.
• Visit the Grandstream Firmware Download page and update the phone to the latest firmware.

1. Test Account Registration

• Navigate to Menu > Status > Account Status.
• Ensure the SIP account is registered. If not:
  • Check the SIP server address, username, and password in the phone's settings.
  • Confirm the SIP server is reachable and operational.
  • Verify firewall settings to ensure SIP traffic is not blocked.

Check Audio Settings

• Test the microphone and speaker:
  • Handset/Headset Issue: Switch between the handset, headset, and speaker modes.
  • Volume Issue: Adjust the volume using the phone’s volume buttons.
• If no audio:
  • Check codec settings (G.711, G.729, etc.) in the SIP account.

Factory Reset

1. Navigate to Menu > System > Operations > Factory Reset.
2. Confirm the reset (this will erase all custom settings).
3. Reconfigure the SIP account details after the reset.
    

Common Problems & Fixes

• Phone Stuck on Boot Screen
  • Unplug the phone, wait 10 seconds, and plug it back in.
  • Update the firmware using the recovery mode.
     
• No Dial Tone
  • Check that the SIP account is registered.
  • Test the phone with another Ethernet cable or port.
     
• Calls Not Connecting
  • Verify NAT traversal settings (e.g., STUN or Keep-Alive) in the SIP configuration.
  • Check for any blocked ports:
    • UDP: 5060 (SIP signaling).
    • RTP: Range (commonly 10000–20000 for media).
       
• Display Issues
  • Adjust the LCD screen brightness in Menu → Preferences.
  • If the display is unresponsive, update firmware or perform a factory reset.