SIP ALG: Why It Breaks VoIP and How to Disable It
If you’ve ever encountered one-way audio, dropped calls, or registration failures in your VoIP deployment, there’s a good chance SIP ALG is the cause. Often enabled by default on routers and firewalls, SIP ALG tries to help — but usually makes things worse.
Let’s unpack what SIP ALG is, why it causes problems, and how to turn it off.