Known Issues:

  1. DHCP Auto-IP-Reservation is on by default which can cause "Network is down" or "DHCP Failed" errors on Polycom phones.
  2. SIP ALG is enabled by default.
  3. We have tested and confirmed on several cases that the software firewall blocks phone registration if enabled because the stock firewall rules only allows SIP signaling through port 5060.
    • The software firewall is actually disabled by default because it can cause phone and other problems.
    • The gateway doesn't allow changing the the SIP firewall rule port to 6060 or 6061 for Secure SIP, which Intermedia phones use.  Custom rules cannot be created as well so the software firewall needs to be disabled.
    • This does not mean your network is left unprotected.  Your network is still protected by the NAT firewall.  Disabling the firewall above just disables the stock firewall rules that block phone registration.
      • If you are concerned about security, then we strongly recommend you purchase a firewall that will allow you to create custom firewall rules, which will give you far greater security than this ISP-provided device.  A ZyXEL USG-series firewall or SonicWall are excellent options.

Temporary Resolution:

  1. Login to the gateway. 
    • The default IP address is
  2. Click on Advanced Setup > Security on the left-hand side of the page > Firewall.
  3. Stealth Mode > Disable.
    • This step is optional, but it's needed to allow your gateway to respond to our Call Quality Monitoring Server. 
    • This gateway does not allow creating a custom rule that will only respond to our server. 
    • It instead bundles the 'WAN Ping response' setting that we need into what the gateway calls 'Stealth Mode'.
    • If you are concerned about security, see the Known Issues section above.
  4. Security Level > Set it to Off.
    • This is the default setting.
  5. Enter the following URL into the address bar of your web browser:
      • Note: If your gateway's address is not using the default IP address of, then you will need to change the URL to use the correct IP address.
    • Click on SIP ALG > Disable > Apply.
  6. Click on Advanced Setup at the top of the page > under IP Addressing > DHCP Settings:
    • Under "1. Set the DHCP server state" -> verify DHCP Server is set to Enable.  
      • If it is set to Disable, then you will need to find out what the DHCP server is on your network.
      • It will likely b another device on the network such as a Windows Server or another router. 
      • Contact your IT for assistance.
    • Scroll down to "4. Automatically set DHCP reservations on DHCP IP allocation" > Disable.
      • We recommend leaving this option disabled as it can cause "Network is Down" and "DHCP Failed" errors on phones, depending on your network setup.
  7. This step is needed only if you have or plan to purchase Polycom phones. 
    • Note: You may need to reboot your computers and other devices on your network after making this change. Make sure to do it at a time when you can afford to be offline.
      • Under DHCP Settings > scroll down to "5. Set DNS servers allocated with DHCP requests" > Select Custom Servers > Enter the following:
        • Primary DNS:
        • Secondary DNS:
      • Click Apply. 
      • Wait for the gateway to save the changes.
      • Reboot all Polycoms phones. 
      • Check each computer and other network devices to verify they can still browse the internet. 
        • If any cannot, reboot them. 
        • Windows computers may require running the following command from Command Prompt to restore their internet connection:
          • ipconfig /flushdns

Permenant Resolution:

If any of the above options are not present then purchase a recommended router:

  • Purchase a recommended router  if you do not have one already.
    • Intermedia cannot setup the new router for you, but your IT or the manufacturer of your new router can help you.  They will need to move settings from the old to the new router to ensure your computers and other devices on the network work properly.
    • Regarding DSL connections, you will need the "PPoE" username and password.
  • Call CenturyLink to bridge your internet gateway to your new router.
    • Note: It is at the discretion of the ISP, whether or not they will allow the modem to be bridged. If they choose to deny the request, then the above resolution will apply.

Additional Resources:

  1. Recommended Routers
  2. Recommended Switches
  3. Recommended LAN Configurations
  4. Network Ports and Protocols for HPBX Phones