Obviously there are enough people out there who fall for this scam to justify keeping the boiler rooms in business. My wife got a panicked call from her cousin in NJ last week who just received one of these calls, fell for it and actually went to Walmart. Luckily the Walmart she went to doesn't do Green Dot anymore and wouldn't accept credit cards for money transfers so no money was actually sent.
Why this woman who is on disability due to a brain tumor and haven't worked in years would believe she actually owed the "IRS" money is beyond me, but she calmed down when I got on the phone and explained that it is a scam, the number is a VOIP number ("Do you remember how you called us on a local 908 number in Montreal for a while?"), these assholes are in India or Pakistan and the only reason they knew her address and that there were a Walmart near by was because her phone is listed and these people know how to use Google maps, too.
At least the guy actually stayed on the phone while she went to Walmart, so she wasted a good chunk of his time. Unbelievable.