Known Issues

  1. SIP ALG is enabled by default. Some firmware versions have a bug that do not allow disabling SIP ALG.
  2. Load-balancing 2 WAN interfaces will cause intermittent call failures. Assigning the phones to use only 1 WAN or using WAN failover instead is required.
  3. We need more information on this router to find out if the other basic router requirements can be made on this router.
    • Contact Intermedia Voice Technical Support so they can better document other necessary changes that need to be made to this router.


  1. Go to Advanced > NAT > ALG
    • SIP ALG: Disable.
    • Click Save.
    • Note: if SIP ALG goes back to Enabled after pressing Save then the current firmware version on the firewall has a known bug. To resolve, you will need to contact TP-Link support and get the latest firmware release.
  2. This optional step is needed for call quality monitoring and troubleshooting purposes:
    • Go to Firewall > Attack Defense > Attack Defense
      • Block Ping From WAN: Uncheck.
      • Click Save