Skype for Business iOS Client sign in issue
I had the problem that users of iOS devices couldn't log in to the Skype for Business Client on their devices. The reason of the problem was very simple. iOS clients doesn't support the basic NTLM authentication method. Resolution Check the web service configuration from the Skype for Business Server with the following steps: Start the Skype for Business Management Shell and view the web service settings with the command " Get-CsWebServiceConfiguation " Change the settings with the command " Set-CsWebServiceConfiguration -UseWindowsAuth Negotiate " (Default setting is NTLM) Check the new configuration with the command from Step 1 Now the iOS users can sign in again to Skype for Business Client. Good luck!