Problems on Unifi USG Networks Where SIP Traffic is Blocked

Running SIP from behind your EdgeRouter or USG? Having call quality problems or can't initiate calls? Disable your SIP ALG (application layer gateway). The SIP ALG is supposed to help broker SIP sessions through NAT (network address translation) but usually breaks the calls instead.

Here we'll walk through how to disable the SIP ALG if you have a USG (via the UniFi software) or if you have ANY EdgeRouter from Ubiquiti Networks. Loss of audio, dropped calls, and one-way talk path are usually symptoms of an ALG that needs to be disabled.

Most providers recommend disabling SIP ALG.

The latest version of UniFi allows you to flip a switch to turn off the SIP ALG. You can disable it via the config tree or command line for the EdgeRouter. From the command line, you would type configure to go to edit mode and then issue the command: set system conntrack modules sip disable

USG STEPS:

1. Open a web browser and navigate to the Ubiquiti (USG/UBNT/UNIFI) User Interface.
2. Log in using your administrator credentials.
3. Go to "Routing & Firewall":
   • Locate and click on the "Routing & Firewall" option in the main menu.
4. Navigate to the "Firewall" tab:
   • In the Routing & Firewall section, click on the "Firewall" tab.
5. Access the Firewall settings:
   • Locate and click on the "Settings" option.
6. Disable SIP (Session Initiation Protocol):
   • Find the SIP setting and set it to "Off" to disable SIP.
   • Ensure that the changes are saved or applied, if prompted.
7. Disable H.323:
   • Locate the H.323 setting and set it to "Off" to disable H.323.
   • Make sure to save or apply the changes, if required.
8. Verify the changes:
   • Confirm that the SIP and H.323 settings are set to "Off" by checking the corresponding status or indicator.
9. Close the Ubiquiti (USG/UBNT/UNIFI) User Interface:
   • If you have finished making the necessary changes, you can close the web browser or log out from the interface.