FortiGate Next Generation Firewall utilizes purpose-built security processors and threat intelligence security services from FortiGuard labs to deliver top-rated protection and high performance, including encrypted traffic.
Description This article describes the situation when users are facing one way audio after FortiOS upgraded to 7.2.0.
Scope FortiGate version 7.2.x.

Disable SIP ALG and SIP session helper by running the following commands :


1) To disable SIP ALG:


FGT# config sys setting

FGT set default-voip-alg-mode kernel-helper-based


2) To disable SIP session helper:


FGT# config sys session-helper



Find the entry which shows 'set name sip' by default it is entry number 13:


FGT(session-helper) delete 13

FGT(session-helper) end


3) Delete all the VOIP sessions, by finding the policy id which allows VoIP traffic and clearing them using the below:


FGT# diag sys session filter policy <policy-id>

FGT# diag sys session list <----- To know the number of sessions for this policy.

FGT# diag sys session clear


4) Test with an audio call.