Integrating Lync 2013 with Exchange 2013 OWA using UM Certificate

In this article we'll go through integrating Lync 2013 with Exchange 2013 OWA utilising the existing Unified Messaging certificate.

Scenario
Exchange 2013 multi-role server has a public signed wildcard certificate *.domain.com being used for client access. Internally CA signed certificate is installed for Unified Messaging with the Exchange server fqdn in the subject and SAN (trusted by the Lync server).

Goal
Exchange 2013 client access server integrated with Lync 2013.

NOTE - If you don't have a unified messaging certificate installed with the server FQDN in subject & SAN, you will need to create a new certificate request, then get it signed by your internal CA to be used for the Lync/OWA integration.

Exchange Steps

1. Enable the OWA virtual directory for instant messaging
Run this in Exchange Management Shell:
Get-OwaVirtualDirectory | Set-OwaVirtualDirectory -InstantMessagingEnabled $true -InstantMessagingType OCS

Whiteboard not Working on Fresh Lync 2013 Standard Edition Server

I came across this when deploying Lync to a Server 2012 R2 for the first time. Voice, video calls and desktop sharing was working as expected. However when trying to open a whiteboard the client was showing a generic 'Network issues' error message. 

When trying to open the whiteboard, the following errors were logged on the front end server:

 Event ID 51021 , Source LS MCU Factory

The MCUFactory failed to find an Web Conferencing Server to service an web conferencing modality request.

Cause: All Web Conferencing Servers are unavailable or overloaded.

Resolution:

Verify that all Web Conferencing Servers are available and not overloaded. If overloaded deploy and extra server to distribute load.

Event ID 32069 , Source LS User Services

The Mcu Factory returned failure for a request sent to it. Conferencing requests for this Mcu type will be retried but if this error continues to occur conferencing functionality will be affected.

Mcu Type: data-conf

Cause:Mcu factory not being provisioned or functioning incorrectly.

Resolution:

Ensure that the Mcu Factory is provisioned and functioning correctly. If any network related errors are reported by the Mcu Factory ensure that they are resolved.

  

Now these errors weren't exactly helpful, as this was a new install of Lync 2013 so we had a 10 pilot users on there. So there is no way it could be an overloaded conferencing server.

I started looking at Lync 2013 with 2012 R2 issues and came across