Windows 8 tablets/laptops WITH Windows Phone?

I'm not sure if this is abstract/impossible, but surely a good step forward would be this sort of integration?

Imagine a tablet, running Windows 8, but also somehow also running Windows Phone 8 on the side. I'd be a killer if they could put some Windows Phone compatible internals inside and run Windows Phone 8 from those, meaning you could put your sim card in and take calls/make calls and text using your tablet - without having to use WIFI or get an additional 3G plan. I'm talking about actual calls through your carrier's infrastructure.

I don't think i've articulated what I mean very well. But, surely, if Nokia could pull this off, they'd be on to a winner?