Skype Room System sign-in failed due to untrusted domain


If you get the following message when trying to sign in to Skype for Business on a Skype Room System, chances are the user domain ([email protected]) does not match that on the certificate (e.g.

“Sign in failed due to untrusted domain”

The Skype for Business Windows client prompts you in this situation and you can take action to trust the certificate. In Skype Room System this does not happen, and you need to manually add a registry key.

To do this you need to log in as an admin to the Windows desktop. Open registry editor and navigate to the following path:


  1. Right-click the SkypeRoomSystem container and then select New > String Value
  2. Type TrustModelData and then press ENTER
  3. Right-click TrustModelData and then click Modify
  4. In the Value date box, add the name of the domain that appears on the Lync Web Service certificate – this value supports a comma-separated list of servers to trust if you have more than one
  5. Close the Windows Registry
  6. Click Apply and Restart to save your changes


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