Troubleshooting 
539 
  Ensure that the Ethernet cable is plugged into the Internet port on the IP phone and 
the Ethernet cable is not loose. 
  Ensure that the Ethernet cable is not damaged. 
  Ensure that the IP address and related network parameters are set correctly. 
  Ensure that your network switch or hub is operational. 
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The LCD screen prompts “No Service” message when there is no available SIP account 
on the IP phone. 
Do one of the following: 
  Ensure that an account is actively registered on the IP phone at the path 
Menu->Status->More->Accounts. 
  Ensure that the SIP account parameters have been configured correctly. 
Press the OK key when the IP phone is idle to check the basic information (e.g., IP 
address, MAC address and firmware version). 
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Do one of the following: 
  Ensure that the target firmware is not the same as the current firmware. 
  Ensure that the target firmware is applicable to the IP phone model. 
  Ensure that the current or the target firmware is not protected. 
  Ensure that the power is on and the network is available in the process of 
upgrading. 
  Ensure that the web browser is not closed or refreshed when upgrading firmware 
via web user interface. 
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Check if the IP phone is configured to obtain the time and date from the NTP server 
automatically. If your phone is unable to access the NTP server, configure the time and 
date manually.