There is an error when establishing a meeting between Skype Business (Lync) on-premise and another Skype Business (Lync) on Premise. It does not connect, the conferencing service does not respond.

The conferencing service did not respond. Please Wait and try again.

Windows

WSS is intercepting the Skype for Business (Lync) traffic.

Here is a list of the destination URLs that need to be bypassed for Skype for Business (Lync) to work properly. 

You can access the SSL exception list by doing the following:

Log in to Portal, then go to Service > SSL interception > SSL interceptions Exemptions, in "Destinations" click "Add" and either input the URLs one by one or import a .txt file.

Press the "Activate" button after having added the domains.

Add Individually or import to portal via txt file.

lync.com

cqd.lync.com

infra.lync.com

online.lync.com

resources.lync.com

config.skype.com

skypeforbusiness.com

pipe.aria.microsoft.com

config.edge.skype.com

pipe.skype.com

s-0001.s-msedge.net

s-0004.s-msedge.net