This has been going on since June 2008 and they've only just caught on? http://www.flyertalk.com/forum/milesbuzz-370/ - half a million views for this topic

Years ago there was a promotion for Virgin Cola which gave out free phone cards with 5 minutes worth of calls and I questioned why someone would pay to top their cards up at £50 a time to make calls that were charged at a standard rate of 15pence a minute.
Turns out the calls were being made to mega-premium numbers that cost £1.50 a minute and up. Someone could set up a line, call themselves until the card ran out, pocket the profit, top the card up again and repeat and repeat and repeat.
I'd figured this out less than a week after the promotion went live - I kept on and on telling management what had happened and pushing them to do something.
Nothing - I'm sure they were delighted that they were exceeding their sales
targets.
This went on for months. Eventually Accounts must have finally got the phone bill.
All it took to solve was a short piece of programming that barred any calls made with certain numbers.
The business hit the skids shortly afterwards and was bought by a US company.