I have a Lync 2013 environment that I'm standing up and an OCS 2007 R2 environment where all my users are.  The Lync and OCS servers are in different subnets and seperated by a strict firewall.   What ports specifically need to be open betwen Lync Front End servers and OCS Front End servers?

I have looked at the Port Requirements documents and they list all ports used but thus far I'm unable to find OCS/Lync Front End to Front End requirements.

As is, the problem that I'm trying to resolve is OCS pool users are not able to see Lync pool users presence or initiate a IM conversation.  Lync pool users are able to see OCS pool users presence and can initiate a IM conversation with

The Port requirement still the same between Lync and OCS only the special ports for OCS compatibility are needed in addition.

The easiest way is to look on the firewall log, to find the blocked ports.

Most common ports should be open between all client and server network.

These are not a complete List, but thPorts should be oppened

443,3478,5061,used mediaports (1024-65555),135,5060-5082, 6891-6901

https://technet.microsoft.com/en-us/library/gg398833.aspx?f=255&MSPPError=-2147217396