Problem: You logon to The Dial-in Conferencing Settings page ( https://<cwaserverwebsitefqdn >/dialin) powered by Communicator Web Access 2007 R2 and Sign in and the Personal Identification Number information as shown by the Assigned Conference Information is blank or empty and the following error...

If you are planning to have external CWA users that will initiate desktop sharing you must configure a CWA external virtual server and OCS Access Edge Server to include the A/V Edge Server role.  Reason is that an internal virtual server will not provide Edge SDP candidates required for the connection...