With but $1,500 worth of equipment and some ingenuity, security researcher Chris Paget can create his own cell phone tower.

Here's the catch, however: The tower itself isn't real. It's a fake recreation of a GSM base station that allows Paget to overpower the actual signals from real-life base stations. The end result? Cell phones connect to PagetNet—or whatever name he's assigned his creation—thinking that they're accessing an actual cell phone tower.

When that happens, Paget can listen in to the conversations and/or record them at his leisure. His device—an International Mobile Identity Subscriber catcher—bounces the call to an actual cell phone tower and the user is none the wiser, save for the fact that all inbound calls now go directly to said user's voicemail as the carrier considers the actual phone off-network.

Paget showed off his device at this year's Defcon convention in Las Vegas after making quite a few consultations as to the actual legality of his talk and demonstration. The trick only works against AT&T and T-Mobile customers in the United States, as Verizon and Sprint both use CDMA technology to power their networks—as mentioned, Paget's spoof only works across GSM-based networks.

As well, the exploit doesn't work for those running on 3G connections. However, Paget noted in his talk that it's easy to overpower a 3G network with a noise generator—which he also happened to have on-hand, but didn't use—to force phones to revert to 2G connections. Once that happens, they're prime targets for Paget's exploit, should he overpower the legitimate signals emanating from local cell towers.

"There's a good chance you won't even know about it when it happens," said Paget during his presentation, a snippet of which can be found below.

"As far as your cell phones are concerned, I'm now indistinguishable from AT&T."