SIP ALG broken on PFSense

tmittelstaedt · April 21, 2026, 4:28pm

I ran across this and figured if anyone has a PFSense firewall they are trying to use with VoIP trunks they may have need of the following.

TLDR: PFSense update version 25.11.1 broke SIP. The fix is:

System > Advanced > Networking - then scroll down and check the box to “Disable hardware checksum offload.” Then save and reboot the box.

Also a possible fix reported to work:

System → Advanced → Firewall & NAT and changing the Firewall Optimization Options to Conservative

See the following:

kierknoby · April 23, 2026, 9:01am

This post has probably saved me hours of trying to figure out what’s wrong, for something I am about to pick up again after a few months. Thanks Ted.

tmittelstaedt · April 25, 2026, 8:32pm

Test it both ways for sure! Glad I could help!