Exchange Connection Error in Lync

From time-to-time, I do come across Lync clients with this small exclamation mark in the lower right corner indicating an Exchange Connection error:

 

There is plenty of information and troubleshooting guides related to this problem on the Internet, but most of them deal with central problems in the Lync/Exchange topology addressing all the users housed on that topology.

 

I do have a small dirty trick that will help 90% of the issues where this happens on a single computer/user:

1. Exit Outlook
2. Exit Lync
3. Start Regedit
4. Navigate to and delete the following Key:
1. Lync 2010:
   HKEY_CURRENT_USER\Software\Microsoft\Communicator
2. Lync 2013
   HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Lync
3. Skype for Business
   HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Lync
5. Start Outlook and Lync

Now it’s time to grab a cup of coffee and wait 5-10 minutes for the Lync client to establish contact with your Exchange environment. You will see this in Lync Configuration Information (rightclick on Lync in System Tray):


Lync waiting for Exchange connection

If you have separate mail and sip domains, it could be necessary to set the DisableEmailComparisonCheck variable:

Set-CsClientPolicy -DisableEmailComparisonCheck $true

 

 

If you still have the problem, it’s time for a deeper dive into primary SMTP addresses, Lync EWS url’s, trusted sites in Internet Explorer or maybe just call a friend :)



Searching for Regedit in Windows8




Starting Regedit from RUN in Windows7/XP

Deleting corresponding Key in Regedit

 

Lync Inter Trunk Routing causing loop

Problem description

All out of sudden, I noticed that Lync 2013 was looping PSTN calls to unattended numbers out to the SIP trunk. This was causing a loop situation when the SIP trunk provider returned the call to Lync.

This was causing a high Audio Failure Trend in the Lync Monitor reports:

The details found in the Lync Monitor reports was specific about the loop detection:

Gateway responded with 482 Loop Detected

Wireshark on the Mediation Server would also pinpoint this loop:

Several loops before call rejected

Loop Detected by SIP provider 

Solution

After going through all the obvious troubleshooting in order to address this problem, I tried to implement the Lync Announcements for Unassigned Numbers. This was working Ok when calling the unassigned number from a Lync client, but incoming PSTN calls to an unassigned number did still lead to the Loop Detected error!

I came across D(one) IT's article named PSTN to Lync 2013 Unassigned Number Failure. This article made me create a Lync Trunk with no PSTN usage records:

 



After syncing the Lync Topology I noticed that the Lync Announcement for Unassigned numbers was working as expected on incomming PSTN calls:

When this was working ok, I did disable the Lync Announcements for Unassigned Numbers. This stated that the loop situation also got fixed by the Lync Trunk With no PSTN usage records. Lync is now rejecting the call without re-routing it:

 

"Inter-Trunk Routing" in Lync 2013 is an exciting new feature in Lync 2013 that allows Lync Server to be the central call processor for a multi-PBX deployment, but it did cause some problems in this topology with a single Lync topology connected to PSTN through a single SIP Trunk. More information about Inter-Trunk Routing can be found at the following resources:

• Mastering Lync: Inter Trunk Routing Deep Dive
• UCKen: Inter-Trunk Routing in Lync 2013
• What's New in Microsoft Lync Server 2013 : Voice Enhancements - Inter-Trunk Routing