Assume that you enable the airplane mode on an Android device that has Microsoft Lync 2010 for Android installed. Then, you turn on Wi-Fi, and connect the device to a working Wi-Fi network. In this situation, you cannot sign in to Lync 2010 for Android.
To resolve this issue, install the following update:
2705496Description of the cumulative update package for Lync 2010 for Android: February 2012