A prevailing feature of the ongoing War on Privacy is a technological game of leapfrog. A technical innovation that protects privacy (or reduces it) leads to a countermeasure to temporarily restore equilibrium. Then another innovation comes along, and the cycle repeats.
Such is the story of caller ID, a technology that originated in the early 1990s. From the outset, you could shield your phone number on a call recipient's caller ID screen (at least in the United States) by dialing *67 before you dialed. Alternatively, you could ask your phone carrier for caller ID blocking for all outgoing calls.
Naturally, there were exceptions. Caller ID doesn't block calls to 800 numbers, because the recipient pays for the calls. It doesn't work for 900 numbers, either. And apparently, calls to law enforcement and other emergency services (e.g. 911 calls) aren't blocked, either.
Privacy advocates didn't like caller ID for obvious reasons. Advocates for victims of domestic violence insisted that caller ID blocking be made freely available. Thanks to their efforts, it was.
On the other hand, some people didn't want to receive calls they couldn't identify (e.g., from telemarketers, and old flame, or whoever). So telephone companies began to offer "anonymous call rejection" services. If a call comes in without a caller ID, the call originator must unblock caller ID to complete it.
The next step in this technological game of leapfrog came when caller ID "spoofing" services sprang up. These Internet-based services allow privacy seekers to assume the identity of another caller. For instance, you could make it appear that your call is originating from the White House, the FBI, or anyone else. Whatever number you tell the spoofing service to insert is what appears on the recipient's caller ID display.
The latest innovation threatens to make caller ID blocking obsolete. A new service called TrapCall (http://www.trapcall.com) allows cell phone users to unmask blocked caller ID on incoming calls. You can obtain the caller's phone number—and in some cases their name and billing address as well.
The basic service is free, although it currently works only with AT&T and T-Mobile subscribers in the United States. It works by exploiting the fact that calls to 800 numbers aren't anonymous. So when you receive a blocked call on your TrapCall-enabled cell phone, it's automatically routed to an 800 number and back to you, in a matter of seconds. The caller originating the blocked call only hears the phone ringing—there is no clue you're unmasking his or her identity.
For the moment, the only way I know of to reliably defeat TrapCall is to use a caller ID spoofing service—which one of TrapCall's affiliates, SpoofCard (http://www.spoofcard.com) will gladly provide. Or you can make your call from a payphone—or borrow someone else's phone.
Perhaps someone will come along with another technology to defeat caller ID unblocking services like TrapCall. But until that happens, before you pick up the phone, ask yourself if you're willing to have the recipient of your call knowing not only your phone number, but also your name, and where you live.
Copyright © 2009 by Mark Nestmann
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