Why Robo-Calls Can't Be Stopped

'When your phone rings, there's about a 50 percent chance it's a spam robo-call,' reports the Washington Post. Now a computer science professor who's researched robo-call technologies reveals the economics behind automatically dialing phone numbers 'either randomly, or from massive databases compiled from automated Web searches, leaked databases of personal information and marketing data.'
It doesn't matter whether you've signed up with the federal Do Not Call Registry, although companies that call numbers on the list are supposed to be subject to large fines. The robo-callers ignore the list, and evade penalties because they can mask the true origins of their calls.... Each call costs a fraction of a cent -- and a successful robo-call scam can net millions of dollars. That more than pays for all the calls people ignored or hung up on, and provides cash for the next round. Casting an enormous net at low cost lets these scammers find a few gullible victims who can fund the whole operation...
Partly that's because their costs are low. Most phone calls are made and connected via the Internet, so robo-call companies can make tens of thousands, or even millions, of calls very cheaply. Many of the illegal robo-calls targeting the United States probably come from overseas -- which used to be extremely expensive but now is far cheaper...
Meanwhile, the Federal Communications Commission has been asking U.S. phone companies to filter calls and police their own systems to keep out robo-calls. It hasn't worked, mainly because it's too costly and technically difficult for phone companies to do that. It's hard to detect fake Caller ID information, and wrongly blocking a legitimate call could cause them legal problems.
The professor's article suggests guarding your phone number like you guard your credit card numbers. 'Don't give your phone number to strangers, businesses or websites unless it's absolutely necessary.'
'Of course, your phone number may already be widely known and available, either from telephone directories or websites, or just because you've had it for many years. In that case, you probably can't stop getting robo-calls.'

Read more of this story at Slashdot.