Make sure that the DNS records for the on-premises deployment of Lync Server are set up correctly. If authentication is successful on the portal, go to the next step.

To do this, try to sign in to the Office 365 portal. To resolve this issue, follow these steps: The user account wasn't provisioned in Skype for Business Online. The user isn't licensed for Skype for Business Online in the Office 365 portal. The user isn't enabled for Lync in the on-premises deployment. The user wasn't moved from the on-premises Lync pool to Skype for Business Online. In a hybrid deployment that has an on-premises Lync Server deployment and Skype for Business Online, the DNS records for Lync Autodiscover must be pointed to the on-premises Lync server. Lync Autodiscover DNS records are set up incorrectly. This includes the Microsoft Office 365 portal. Single sign-on (SSO) isn't set up correctly, and the user or users can't sign in to any Office 365 service. This issue may occur if one or more of the following conditions are true: Users who were moved from an on-premises Lync Server deployment to Skype for Business Online (formerly Lync Online) can't sign in to Skype for Business Online. Planning for Lync Server 2013 Hybrid DeploymentsThis article doesn't cover deployment or configuration scenarios for Lync Server. Steps to Prepare and Deploy Lync Server 2013 Hybrid Environment Note This article assumes that you configured your on-premises Lync Server hybrid deployment and completed all the prerequisites that are described in the following Microsoft TechNet articles:

Unable to sign into skype account