I will try to give you my experience on troubleshooting this issue.
First of it is important to understand how the EWS integration works in LYNC.
Lync uses the following DNS-based discovery method
So wery often I see customers having a perfectly good working autodiscover setup, seen from Outlook because it utilizes SCP in AD – and when LYNC is deployed integration fails.
So which features are serviced by EWS:
Voice Mail Playback
High-Resolution Photos on contacts
Meeting tab – with meetings from calendar
Contact Information Presence based on Calendar Information
And Unified Contact Store
So EWS is extremely important for LYNC to work correctly
And therefor DNS based autodiscover needs to be setup corrently.
Please note that if EWS fails LYNC will failback to MAPI for some features
Also internal URL for EWS needs to be configured on Exchange – more info: http://technet.microsoft.com/en-us/library/aa997233(v=exchg.150).aspx
When all the above is set correct , and EWS integration still fails – well.. start diggin 🙂
First off, lets get an idea of what LYNC actually tries to do.
Sign in to local pc as the failing user, and with LYNC client running, find the LYNC icon in systray – press CTRL and rightclick icon and select “configuration information”
Check to EWS URL lines, and EWS status.
IF EWS not deployed shows up then first thing to check is this reg key:
Go to HKLMsoftwareMicrosoftofficeoutlookaddinsUCAddin.LyncAddin.1
Make sure that value of “LoadBehavior” is = 3, if not then change it to 3
Note: It might be under HKLMsoftwareWow6432NodeMicrosoftofficeoutlookaddinsUCAddin.LyncAddin.1