The unregistered line error is a general error that happens with Polycom VVX business media phones due to incorrect LAN configuration, network fluctuations, or issues with SRTP services. As a result of incorrect settings, the phone cannot authenticate with the SIP proxy. There are a few ways to troubleshoot and solve this error and improve your personal productivity (or that of your office staff). Check the firmware version on your Polycom VVX 400 Series phone color display using the screen controls and make sure that the phone is using a supported version. Contact your provider to see which firmware version you should be using. Power-cycle the phone: Unplug the phone from the power line. Wait 60 seconds. Plug the phone back into the power source. Let your phone start and reacquire proper configuration settings. Go through the following troubleshooting steps: Check firmware. Check your firewall settings. Check your local network settings. Contact your phone provider to obtain correct settings for the LAN network and firewall or use an ethernet cable. If the above instructions don’t solve the problem, you can try changing the boot server: Write down the Polycom IP phone’s IP address. Open up a web browser on a computer that uses the same network. Enter the phone’s IP address to access the web interface for phone configuration. Click on Settings > Provisioning Server > DHCP Menu. Locate the Boot Server field and select Static. Click Save. Let your phone restart and obtain the correct configuration.