Symptoms
Assume that you make a call by using a telephone that is running Microsoft Lync 2010 Phone Edition for Aastra 6721ip and Aastra 6725ip, and you press the OK button. Or, you press the Select button during a call that you make by using a telephone that is running Lync 2010 Phone Edition for Polycom CX500, Polycom CX600 and Polycom CX3000. In this situation, the call disconnects unexpectedly.
Resolution
To resolve this issue, install the following cumulative update.
For Aastra 6721ip and Aastra 6725ip telephones:
2529978 Description of the cumulative update for Lync 2010 Phone Edition for Aastra 6721ip and Aastra 6725ip: April 2011
For Polycom CX500, Polycom CX600 and Polycom CX3000 telephones:
2529977 Description of the cumulative update for Lync 2010 Phone Edition for Polycom CX500, Polycom CX600 and Polycom CX3000: April 2011
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
