‘When I’m calling you, oo-oo-ooo, oo-oo-oo…..,’ with an attractive sub-continental accent. ‘ Good morning. You owe my company 500 bucks. So pay up very quickly before we doorstep you. Thank you very much.’
Now I’m pleased to report that these distant, unsolicited callers haven’t yet discovered the wilds of Vikingland – perhaps owing to their concentration on English-speaking victims – but a word to the wise – you might get a call yourself before long.
Witness the Times of India: http://timesofindia.indiatimes.com/world/us/Indian-call-centres-used-for-5m-debt-collection-scam/articleshow/11999098.cms
Boadicea's Chariot 
When I’ve had dealings with the subcontinent’s call centres, I usually have difficulty understanding what is being said. So if I got such a call, I would simply say “I’m sorry, I can’t understand you.” Why on earth would people pay money they don’t owe?
Yep. You have to wonder.