How to Disable SIP ALG on Unifi USG
Need to disable SIP ALG so that your VOIP telephones in the office work properly?
In your Unifi Controller or Cloud Key browse to ‘Routing & Firewall’ -> ‘Firewall’ -> ‘Settings’.
Switch off the H.323 and SIP Conntrack modules and Save the Settings.

If you don’t have these options on your controller please backup your configuration and upgrade to the latest version.
20th May 2019
In the above instructions H.232 should read H.323
23rd May 2019
Thank you its been updated 🙂