Mallu123
It is really Funny why did they asked u'r friends SSN in Mumbai ,why they are bother about this , tell your friend to keep watch on his Credit Report for unknown transaction .
Just think about this there can be racket also where by they ask SSN at that time they have our passport containing DOB Mother's Name,etc.
Few months back i read posting on this very site that Immigration Personal used to tear pages from passport , so upon arrival they used to harass passenger about the missing page (to make money )
I dont want to scare but , Just can't understand why SSN needed at Mumbai Airport .