A security researcher created a cell phone base station that tricks cell phones into routing their outbound calls through his device, allowing someone to intercept even encrypted calls in the clear.

The device tricks the phones into disabling encryption and records call details and content before they’re routed on their proper way through voice-over-IP.

The low-cost, home-brewed device, developed by researcher Chris Paget, mimics more expensive devices already used by intelligence and law enforcement agencies – called IMSI catchers – that can capture phone ID data and content. The devices essentially spoof a legitimate GSM tower and entice cell phones to send them data by emitting a signal that’s stronger than legitimate towers in the area.

“If you have the ability to deliver a reasonably strong signal, then those around are owned,” Paget said.

Paget’s system costs only about $1,500, as opposed to several hundreds of thousands for professional products. Most of the price is for the laptop he used to operate the system.

Doing this kind of interception “used to be a million dollars, now you can do it with a thousand times less cost,” Paget said during a press conference after his attack. “If it’s $1,500, it’s just beyond the range that people can start buying them for themselves and listening in on their neighbors.”