Equisys technical notes

Technical guidance, explanations and fixes for our products

INFO: Zetafax with Lync Server



ID: ZTN1932

This Zetafax technical note applies to:

  • Zetafax v12.5 and later
  • Zetafax FoIP standard Edition
  • Zetafax FoIP SR140 Edition


This technote gives an overview of the recommended way to implement the Zetafax server within a Lync Server environment.The details for the gateway used or PBX configuration details can be obtained via a specific HOWTO technote for the gateway, which can be found by searching on our website, or via our technical support department.

More information

The Zetafax server does not support the Exchange UM model for integration with Microsoft Lync. The Zetafax server offers a simplified model which does not lose any of the benefits, and is considerably simpler to implement and maintain. Lync server itself does not support fax, as Fax over IP (FoIP) requires special protocols to reliably transmit fax data over an IP network. For this reason the call must not be passed through the mediation server. To enable fax within a Lync environment we recommend that the calls are spilt from the Lync calls at the media gateway. Lync calls are passed to the Lync server using the TCP protocol via a separate trunk to the Zetafax server. For example when using an AudioCodes gateway, an engineer is able to apply the configuration changes to the gateway with only a few gateway setup changes, allowing fax integration without any downtime or interuption to the Lync infrastructure. All faxes are separated from the Lync server, directly routed to the fax server using the T.38 over UDP protocols.

As shown in the diagram above, we recommend creating a separate SIP trunk for the Zetafax server on the gateway/PBX. This allows the routing of fax traffic directly to the Zetafax server using dedicated DDI’s, and the routing of VoIP calls to the Lync Mediation server.  Lync server uses the TCP protocol, wheras Zetafax uses UDP and these are configured using separate SIP trunks.

For a list of compatible gateways for lync server, please see the relevant Microsoft documentation.
For a list of compatible gateways for Zetafax, click here.


Dialogic interopability list: http://www.dialogic.com/Interoperability/fax.aspx

Zetafax Fax over IP: http://www.equisys.com/products/zetafax/fax_over_IP.html

Last updated: 4th April 2013 (AF/MW)

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