Known Issues

  1. We have tested and confirmed on several cases that the software firewall blocks phone registration if enabled because the stock firewallrules only allow 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 customfirewall rules, which will give you far greater security than this ISP-provided device. A ZyXEL USG-series firewall or SonicWall are excellent options.
  2. Certain Firmware versions have SIP ALG enabled by default. If you have this device, please contact Intermedia Cloud Voice Technical Support so we can run our SIP ALG detector tools to verify whether this gateway has SIP ALG or not.


  1. Login to the gateway.
  2. Click on Advanced Setting at the top of the page. Then click on Security on the left-pane menu and choose IPv4 Firewall from a list.
    1. Set the stealth mode state - leave at the default setting, which is Disabled.
    2. Select the IP address or IP addressing type to which the firewall rules should apply - All Dynamic IP Addresses.
    3. Select the Firewall Security Level to be Off. This is the default setting.
    4. Click on Apply to save changes.
    5. If you are concerned about security, see the Known Issues section above.
  3. This step is needed only if you have or plan to purchase Polycom phones.
    • These changes will take your computers, phones, and all other devices online for 10 minutes or much longer if an unexpected problem arises.
    • Make sure to only change the settings below when you can afford to take your network offline:
      • Under DHCP Settings scroll down to "5. Set DNS servers allocated with DHCP requests" and select Custom Servers. Then enter the following: 
        • Primary DNS:
        • Secondary DNS:
      • Click on Apply and wait for the gateway to save changes.
      • Reboot all Polycom 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.
  4. The steps below explain how to disable SIP ALG on most CenturyLink-branded gateways. Please let us know if the instructions below do not work for you:
      1. Enter the following link into the address field of your web browser:
        • If your gateway's address is not using the default IP address of, then you will need to change the URL to reflect the correct address.
      3. Click on Advanced Setting at the top of the page. Then click on Security on the left-pane menu.
      4. Click on SIP ALG and select Disable. Then click on Apply.