When you attempt to enable a mobile device on a management point enabled for mobile devices in System Center 2012 Configuration Manager Service Pack 1, you may see the following error in the mpcontrol.log:
Call to HttpSendRequestSync failed for port 443 with status code 401, text: Unauthorized
This issue can occur if the .NET Framework 4 is installed on the server before IIS is enabled.
To resolve this issue follow the steps below:
1. Open a command prompt with administrative privileges.
2. Run the following command:
%windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_regiis.exe –i –enable
For more information please see: http://msdn.microsoft.com/en-us/library/k6h9cz8h(v=VS.100).aspx
The .NET Framework 4 can be installed side-by-side with previous versions of the .NET Framework on a single computer. If IIS was previously enabled on the computer, the setup process for the .NET Framework automatically registers ASP.NET 4 with IIS. However, if you install the .NET Framework 4 before you enable IIS, you must run the ASP.NET IIS Registration tool in order to register the .NET Framework with IIS and create application pools that use the .NET Framework 4.
Supported Configurations, Prerequisites for Site System Roles section: