Microsoft Lync 2010 is the default client for Lync Server 2010 meetings. Features include presence, contact management, instant messaging (IM), telephony, and greatly enhanced conferencing.

To implement the manager/delegate scenario with Lync 2010, both manager and delegate need to install and use Lync.

Microsoft Lync 2010 Attendee is a rich conferencing client that allows users who do not have Lync installed to fully participate in Lync Server meetings. Lync 2010 Attendee can be installed on a per-user basis, so you can choose to selectively deploy this client, or you can allow users to download and install it as needed.

For details about how to control the conferencing client choices that appear on the meeting join page, see the “Configuring the Meeting Join Page” section in Migration Considerations for Meetings in the Migration documentation.

Microsoft Lync Web App is a web-based conferencing client that supports most Lync collaboration and sharing features and also presenter meeting controls and dial-in and dial-out voice conferencing.

For users who do not have Lync installed, you can offer this conferencing option when it is not practical or possible to install Lync 2010 Attendee. All the in-meeting features except for computer audio, video, and PowerPoint presentations are available to Lync Web App users.

For details about how to control which client options appear on the meeting join page, see the “Configuring the Meeting Join Page” section in Migration Considerations for Meetings in the Migration documentation.

Microsoft Lync 2010 Attendant is an integrated call-management application that enables a receptionist to manage multiple conversations at the same time through rapid call handling, IM, and on-screen routing.

Although previous versions of Microsoft Office Communications Server 2007 Attendant supported both manager/delegate scenarios and receptionist scenarios, Lync 2010 Attendant supports the receptionist scenario only. If necessary, a delegate can use Lync 2010 Attendant to receive calls for the manager, but delegate features are now provided in Lync.

Microsoft Lync 2010 Mobile provides IM, enhanced presence, and telephony for users in your organization who are connecting from a smartphone or a phone running a Professional edition of Windows Mobile.

Microsoft Lync 2010 Phone Edition is software that runs on intelligent IP phones (for example, USB-attached phones) and supports placing and receiving calls, enhanced presence, and client audio capabilities for conferences.

The Online Meeting Add-in for Microsoft Lync 2010 supports meeting management from within Microsoft Outlook messaging and collaboration client. This software is installed automatically with Lync.