Switchvox - How can you fix no audio on Switchvox softphones when using a Fortigate firewall?

If you have a Fortigate/Fortinet firewall on FortiOS 5.2 or later, there is a new option that needs to be set if you are having no audio issues with the Switchvox softphone.

1. Log in to firewall GUI

2. Go to Configuration > System Settings

3. Set default-voip-ALG-mode to kernel-helper-based  (default is proxy)

4. Place test call with Switchvox softphone

Fortinet documentation:
How to disable ALG for SCCP traffic to allow TCP port 2000