Add Exchange Certificate to Lync WebService Trusted Root Store

• Open Outlook Web Access and view the HTTPS certificate.
• On the Certificate Path tab select the top level certificate (e.g. GoDaddy Root) and click View Certificate
• Locate the Thumbprint field and copy the value and paste it to a text editor. Remove all spaces from the thumbprint.
• On the Lync server running the WebService (LYSE) open the Lync Server Management Shell and run the following commands inserting the thumbprint where noted.

Get-CSWebServiceConfiguration

• Note the value of the TrustedCACerts field

$cert = new-cswebtrustedCACertificate -thumbprint “‎Thumbprint_Here” -castore TrustedRootCA
set-cswebserviceConfiguration -trustedCACerts @{Replace=$cert}
Get-CSWebServiceConfiguration

• Again, note the value of the TrustedCACerts field. Verify that it has changed.
• Reboot a Lync phone and verify the calendar is functional.