Cannot sign in to Skype for Business 2015 (Lync 2013) when you register the domain as a vanity domain Content provided by Microsoft Applies to: Skype for Business 2015Microsoft Lync 2013 Select Product Version All Products This issue occurs when the domain name of the SIP user is registered as an Organizational ID (OrgID) and Microsoft account (MSA) domain. Resolution To fix this issue, install the April 4, 2017, update (KB3178731) for Microsoft Skype for Business 2015 (Lync 2013).Note Lync 2013 was upgraded to Skype for Business in April 2015. Last Updated: Apr 4, 2017 Did this solve your problem? Yes No Tell us what we can do to improve the article Submit Thanks! Your feedback will help us improve the support experience.