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You are connected to a corporate wireless (also known as Wi-Fi) network or are signed in to an Office 365 subscription that's enabled for single sign-on (SSO) by using Active Directory Federation Services (AD FS) 2.0. When you try to sign in to Lync Mobile on your Apple iOS-based device (such as an iPhone or iPad), you receive one of the following error messages:

  • Can't verify the certificate from the server. Please contact your support team.

  • Can't connect to the server. It might be unavailable. Also please check your network connection, sign-in address and server addresses.

In addition, when you view the Lync Mobile logs for iOS, you see the following entry:

Lync[13886:300b] ERROR TRANSPORT
/private/CLiveIdUtilities.cpp/155:Converting liveIdError -2147012841 to ErrorCode 570556418


To resolve this issue, install your Enterprise Root CA Certificate on the iOS Device. You can do this manually or by using the Apple Configurator.


The cause of each message is slightly different, but both errors are caused by the inability to verify the authenticity of a certificate or certification authority.

For more information, go to the following Apple website:

Digital certificates - iOS Deployment ReferenceOr, contact Apple Enterprise Support for help with managing your iOS devices.

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.

Still need help? Go to Microsoft Community.

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