From the perspective of the Lync Server on forest A and Exchange UM server in forest B

What firewall ports need to be open from the server perspective?

Specifically does the Lync UM server need to be able to talk to the DCs in forest B directly ( and similarly Exchange UM server to the DCs in forest A)?

Ports such as

Any advice much appreciated

Regards

Alistair

Hi,

As Microsoft Exchange Server and Exchange Unified Messaging (UM) are installed in different forests, firstly you need to configure each Exchange forest to trust the Lync Server 2013 forest.

Here is the steps to deploy Lync Server integration with Exchange UM:

https://technet.microsoft.com/en-us/library/gg425737(v=ocs.15).aspx

For the special ports between two forests you'd better contact Microsoft and there are more experts will help to confirm it. Thanks for your understanding.

Best Regards,
Eason Huang