Windows 10 activation by phone

Windows 10 wants to live connected to the internet, it's clear. But there are some situations where it is not possible or it is mandatory forbidden.
In these cases you have to use the procedure to activate the Windows copy by phone. But how?
The activation menu, in fact, doesn't show clearly this possibility, but a workaround exists.

• Log in using an administrative account
• Type "SLUI 04" in the search box of the menu
• Select and run the application you find

A renewed "Activation by phone" mask should appear and by following the wizard you should able to activate your authentic copy of the OS follow the step by step procedure by phone.

Credits: http://windows.microsoft.com/it-it/windows-10/activation-errors-windows-10