Equisys technical notes

Technical guidance, explanations and fixes for our products

HOWTO: Test Zetafax Online for July 2020 service change continuity



This Zetafax technical note applies to:

  • Zetafax Server (all versions)
  • Zetafax Online


This article describes a change to the Zetafax Online service which is scheduled for 1st July 2020, and how to test an existing Zetafax system before that date to confirm that it will continue to work correctly after the change is made.

More information


Zetafax Online is an add-on for Zetafax systems which enables them to send and receive faxes using a cloud fax service run by InterFAX.  The Zetafax Server computer communicates with the InterFAX service over the public Internet, and this communication is protected using the TLS (Transport Layer Security) protocol.

The InterFAX service currently supports TLS version 1.1 and later.  However TLS 1.1 offers less protection than later versions, and major web browser providers including Google, Microsoft, Apple, and Mozilla have recently announced that they are phasing out support for TLS 1.1 for this reason.

The InterFAX service will stop supporting TLS 1.1 on July 1, 2020.  After that date Zetafax systems using Zetafax Online will only be able to continue sending and receiving faxes if the version of Windows they are running on supports TLS version 1.2 or later.

Windows support for TLS 1.2

Windows 8.1, Windows Server 2012 R2, Windows 10, Windows Server 2016, and later versions of Windows natively support TLS 1.2 for client-server communications over WinHTTP.

Earlier versions of Windows, such as Windows 7 or Windows Server 2012, don't enable TLS 1.1 or TLS 1.2 by default for secure communications using WinHTTP. For these earlier versions of Windows you may need to install an update to use TLS 1.2, although on a system which is already using Zetafax Online it is likely that this will have already been installed with no further action needed.

There is no change in the Zetafax software needed to support TLS 1.2, and no need to upgrade the Zetafax software to prepare for this change.

Testing Zetafax Online before 1st July 2020

Zetafax Online communicates with the InterFAX service using the endpoint ws.interfax.net.  To allow systems to be tested before the switchover a separate endpoint is available at wsnotls1.interfax.net.  This can be used with your live Zetafax Online account, though should only be used temporarily for a short period to test the system.  You can redirect traffic from Zetafax to the test endpoint by doing the following:

  • On the Windows computer which is running the Zetafax Server, run Notepad as administrator
  • Open file “hosts.” in folder “C:\windows\system32\drivers\etc” (or equivalent on that computer)
  • Add the following line to the end of the file:        ws.interfax.net

  • Save the file then close Notepad
  • Run a command prompt, then enter the following command:

ping ws.interfax.net

  • Check that the IP address reported by ping is “” to confirm that the hosts file redirection is working correctly.
  • Run the Zetafax Configuration Program, then display Server settings > Least Cost Routing of faxes > Links.  In the Remote servers list select the Zetafax Online entry then click Edit.  Now display the Account tab then click Test.  Check that the test completes successfully, indicating that the installed version of Windows supports TLS 1.2 or later.  Now close the dialogs and close the Zetafax Configuration program.
  • Send a test fax from the Zetafax Server, and check that it is working correctly as before.
  • Edit the hosts file again by following the instructions above, delete the line which you added previously, then save the file and close Notepad.
  • In the command prompt enter the following command

ping ws.interfax.net

  • Check that the IP address reported by ping is now “” to confirm that the hosts file redirection has been removed correctly and the system is now using the live InterFAX endpoint again.



Last updated: 17th June 2020 (GW) 




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