Equisys technical notes

Technical guidance, explanations and fixes for our products

HOWTO: Setting up Zetafax on a Microsoft Azure hosted server



This Zetadocs technical note applies to:

  • Zetafax version 17.5 and later
  • Brooktrout driver version 6.15.1 and later


This technote will allow users to set up and use Zetafax on a Microsoft Azure hosted server. Brooktrout SR140 has a Network Address Translation (NAT) feature in version 6.15.1 and onwards which will need to be utilised to allow network traffic to flow from the Microsoft Azure hosted server to the SIP trunk gateway. Users will also need to be using Zetafax version 17.5 and onwards.

More information

To allow traffic to flow out of the Microsoft Azure hosted server, Network address translation has to be used to translate the Internal IP addresses of the Azure server to an external IP. When a call is placed out to the SIP trunk, the NAT feature of the Brooktrout driver will allow the SIP trunk to translate the internal IP addresses in the SIP headers to their external equivalent. Essentially, the "To", "From" and "Contact header" fields that go out with your internal address will all be changed to an external address so that the remote SIP trunk gateway can send back its own SIP messages.

Brooktrout driver version 6.15.1 and onwards has a NAT feature which will allow the IP translation to take place. This is included in either the Zetafax Brooktrout update found on the software updates page. 

Please follow the steps below to make use of the NAT feature in the Brooktrout Configuration tool.

  1.  Download and Install Zetafax version 17.5 from the Equisys website if you do not have this version already. You will need to have Software Assurance credentials to download, which is included in the Software Assurance newsletter. If you do not have this, you can contact Equisys support to receive the credentials - Zetafax Software Updates | Zetadocs Software Updates (equisys.com)
  2.  If you already have Zetafax version 17.5, you can receive Brooktrout driver 6.15.1 as a standalone download from the same location as above. Running through the installation will just update the version of the Brooktrout driver. 
  3.  Once installed, open the Brooktrout Configuration tool in Advanced mode.
  4.  Navigate to IP Call Control Modules -> SIP -> IP Parameters -> Click on Show Advanced in the bottom right -> Navigate to the very bottom of the section to find 2 fields that are used for the new NAT feature. Please find a screenshot below highlighting the location.
  5.  Enter these fields with the External IP Address of the Azure hosted server. If you do not have an External IP set up, you can do this via the Azure portal. As far as we are aware, an External IP address must be set up for Brooktrout SR140 to work on an Azure hosted server.
  6.  Save and Apply the configuration.


Last updated: 9th November 2023 (MS)

Keywords: Zetafax, Brooktrout SR140, Azure, NAT, Cloud server

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