Symptom: When logging into the Lync 2013 on an Android or iOS device, you receive the following error:

This version of Lync has been blocked by your system administrator.  Please check for updates or contact your Lync support team.

Solution: This error is caused by not running the latest version of Lync Server 2013.  Make sure you have at least the February Cumulative Update 1 patch applied to your server.  Without this patch, the Lync client will not be able to login.

You can grab a copy of the patch from: http://www.microsoft.com/en-us/download/details.aspx?id=36820

Details on how to install the patch can be found here: http://support.microsoft.com/kb/2809243