Hi,
The reason you're encountering this problem is that the mobile broadband device is embedded, which means it's an integral part of the computer and so doesn't get its own metadata package. In general, a single metadata package applies to a single thing
you can pick up with your hands - for example, a multifunction printer+scanner+fax would get one metadata package because it's one physical object, even though it consists of three separate devices. By this rule, everything that is built into
a laptop or tablet (cameras, mobile broadband, microphones, etc) shares the same metadata package, which is bound to the entire computer.
What you need to do is create a computer metadata package (the document "Device Metadata Package Schema Reference for Windows 8" at http://www.microsoft.com/en-us/download/details.aspx?id=30725,
specifically the section named "Notes for Computer Device Containers", has the details) and add your app's publisher and name to the list of privileged apps for that metadata package, just as you would for a removable device. Then your app will
have access to the WinRT SMS API. If your computer already has a metadata package that was put there by the manufacturer, you will need to edit it and add your app to its privileged app list. Since this will invalidate the existing package's digital
signatures, you will need to enable test signing on that machine using bcdedit.
