Microsoft has released an update for Lync for Mac 2011

This update provides the following improvements:

Support for Lync Online and Lync Server 2013.
Automatic configuration with Office 365.
Voice mail indicator to see the number of voice mails and a list of voice mails.
The ability to play voice mails from the Lync for Mac 2011 client.
Long press 1 to access voice mail.
Enter key now plays the sound for the number sign (#) in Dual-tone multi-frequency (DTMF).
Boss delegate is shown in a group for contacts.
Improved performance for desktop sharing.
Long press 0 for the Plus Sign (+) sign.
The plus sign (+) is now supported from the dial pad.
Dial tone plays when you are disconnected or not connected to a call.
The Lync call window comes to the foreground when you are disconnected.
Retrieval of calendar information is supported.
Conversation history for voice calls is now available.
Support for recording notifications of conversations and online meetings.
Local ring back tone for outgoing PSTN calls is now available.
The Quality of Experience (QoE) XML file will now pass validation for the Voice Quality (VQ) Report functionality.

The update fixes the following issues:

2844262 Error message when you enter a plus sign on the dial pad in Lync for Mac 2011
2851281 You cannot join an online meeting on a Lync for Mac 2011-based device
2844273 Users cannot hear ring-back tone for outbound calls through PSTN in Lync for Mac 2011
2844266 Users cannot retrieve calendar information in Lync for Mac 2011
2844270 User is disconnected from a desktop or application sharing session in an online meeting in Lync for Mac 2011
2844265 An update that lets you view your calls history is available for Lync for Mac 2011
2844271 Users now receive a recording notification when a conversation or an online meeting is recorded in Lync for Mac 2011
2851280 Can't sign in to Lync for Mac 2011 by using an Office 365 account
2851290 Call information is not displayed in the Media Quality Diagnostic Reports for a device that is running Lync for Mac 2011
2851291 Update is available that adds delegate management features to Lync for Mac 2011
2837047 Error message when you try to join an online meeting on a Lync for Mac 2011-based device
2837048 Desktop sharing or video sharing session disconnects when you use Lync for Mac 2011

Additionally, this update also fixes the crash issue in Join Launcher plugin.

  Update for Lync for Mac 2011 - KB2844274