How to remove VOIP helpers for hosted Avaya on Fortinet

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Trying to setup a hosted Avaya solution on Fortinet but having issues? If you have worked with firewalls in the past, you may be familiar with session helpers. Firewall manufacturers typically create these to ease with different types of traffic, especially with multimedia like voice and video. Unfortunately these session helpers can be problematic with certain manufacturers, especially Avaya. In our experience, session helpers often have to be disabled to ensure phone functionality.


For hosted Avaya session helpers must be removed for following protocols:

  • RAS
  • H323
  • SIP


Always remember to backup your firewall configuration before making changes.

Use config system session-helper and then type show to see the session helpers

You can delete them based off their numeric index, e.g. delete 13

Once you’ve deleted all 3 (some may be missing depending on FortiOS version or model), you can simply type end

This is due to how ALG works with session helpers on Fortigates, which affects hosted Avaya. These changes work on 5.2 and 5.4 versions of FortiOS and possibly others. For more information about session helpers, see Fortinet’s article for 5.2 FortiOS.