After Lync Mobile 2013 is installed, users who try to sign in to their organization’s Lync server or to Skype for Business Online (formerly Lync Online) in Office 365 receive the following error message:
You can’t sign-in with this version of Lync. Please install Lync 2010.
If the users are signing in to an on-premises Lync Server 2013 deployment, you must apply Cumulative Update 1 for Lync Server 2013, and mobility must be enabled. For more information, go to the following Microsoft Knowledge Base article: