When an outside user attempts to join a conference created by a Lync user, they have three options available to them.

If the user has Silverlight installed, but not the Lync client or Attendee client installed, then they will be able to join the conference automatically from Lync Web App.

If the user does not have Silverlight installed on their system, they can install the Microsoft Lync 2010 Attendee client. The Attendee client has two flavors, a full version for those with Administrative rights to their system, and a light version for those without administrative rights.

To summarize, when a user connects to the meeting Simple URL (ex: meet.catapultsystems.com) , then depending on the installed clients the following will happen:

· Lync installed: meeting will open in Lync

· Attendee client installed: meeting will open in Attendee client.

· No client installed: meeting will open Lync Web App