Is it possible to port a Skype number onto AT&T prepaid

Good morning All,

I've done a search on topic and not really found an answer so wondering if any of you guys had either (a) done this or (b) knew it wasn't possible. 

So as per the title, I have a number assigned to my Skype account that ideally I'd like to port onto a prepaid AT&T sim. 

Has anyone any experience of doing this? 

Also, just to add to the complication. I did notice on the porting process from AT&T (assuming this can be done) that it asks for the last four digits of a social security number. As a regular visitor but not a resident (I'm British and live in the UK), is this a show stopper? 

Appreciate your thoughts!