It is possible to subscribe to Hotmail/Outlook/Windows live calendar.
1) Login to your Microsoft account.
2) Go to the outlook menu bar and click the top left icon
3) Click the calendar from the dropdown
4) Then click the import button that appears on the top.
From this final screen you can both subscribe ICS files or import to a calendar.
To Subscribe
i) To subscribe click on the menu item on the left-hand-side.
ii) Lastly on the right-hand-side fill out both the calendar URL and a unique name for the calendar. Hit subscribe to add the calendar, a color and charm can also be added.
To Import
a) Click on the menu item on the left-hand-side.
b) On the right hand-side choose from the drop down to add events to a new calendar or an existing calendar. Hit import to add the calendar.