Rayhunter IMSI-Catcher Detector

Tells you when something nearby is behaving like a fake cell tower.

Placeholder illustration. Real photographs go here once we have finished hardware to photograph — we will not use stock images of somebody else's equipment.

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A pocket LTE hotspot reflashed with the EFF's Rayhunter firmware. It sits in your bag or on the dash and watches the signalling traffic between itself and the tower it is attached to. Green bar means that traffic looks normal. Red means it logged something worth a second look.

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Pre-order means we build to order. Nothing is charged through this site — you talk to us first.

GPL-3.0 — source code ships with the unit.

CAPABILITY

What it does

Passively inspects cellular control-plane signalling and flags behaviour associated with cell-site simulators (IMSI catchers) - forced 2G downgrades and suspicious IMSI requests among them.
Shows the whole answer on the device's own status bar: green or blue for clean, red for a logged event. There is no app and no account.
Keeps a local capture you can download as a PCAP from the device's own web dashboard, for expert review or to submit to the EFF's research programme.
Runs on one piece of hardware. No software-defined radio, no Raspberry Pi, no external antenna, no extra receiver to carry.
Receives only. It never transmits as a base station - it is a detector and receiver, not a simulator.

LIMITATIONS

What it does NOT do

Read this part. It is the half of the specification most sellers leave out.

It does not read, record, or decode anyone's calls, texts, or data. It looks at the signalling layer that phones and towers use to negotiate a connection, not at call or data content.
It is not a cell-site simulator and does not transmit as one. If you were sold something described as a "simulator", that is a different and very different-sounding device.
It cannot tell you who is operating a suspicious tower, or why they are doing it.
A red flag is an anomaly worth investigating, not proof of surveillance. A quiet device is not proof you were not surveilled.
Real-world detection effectiveness has not been independently lab-verified against a known cell-site simulator. The EFF built it and maintains it, the community runs it, and detections are genuinely hard to confirm without already knowing an interceptor is present. We would rather you heard that from us than found it on a forum later.
It does not block, jam, or stop anything. It watches and tells you.

HARDWARE

Specifications

Platform

Orbic RC400L LTE mobile hotspot (sourced used/refurbished), flashed with EFF Rayhunter firmware

Detects

Cellular control-plane signalling anomalies - forced 2G downgrade, suspicious IMSI request, and related rogue-base-station behaviour

Interface

On-device status bar (green/blue clean, red event) plus a local web dashboard on the device's own Wi-Fi

Log format

PCAP, downloaded over the device's own access point

Upstream project

EFForg/rayhunter - actively maintained, 56 contributors, commits within days of our last review

Extra hardware needed

None. No SDR, no single-board computer, no external antenna

Options

Spare battery for swap-and-go field use; prepaid data SIM. Whether an activated SIM is strictly required for detection is an open question upstream, so we do not sell it as mandatory

Supply note

The hotspot is a secondhand device. Condition and carrier-lock status vary by unit, so we test and verify every one before it ships

OPEN SOURCE

Licence & attribution

GPL-3.0

Runs Rayhunter, copyright the Electronic Frontier Foundation and contributors, licensed under GPL-3.0. The complete corresponding source for the exact release flashed on your unit ships with the unit, and we do not lock the hardware against you reflashing it yourself.

QUESTIONS WE GET

Straight Answers

Is it legal to own and run one of these in West Virginia?

As far as we can determine, yes. West Virginia puts no licence, permit, or registration requirement on owning a radio receiver, and federal law (18 U.S.C. 2511(2)(g)) permits monitoring readily accessible radio signals. The EFF's own published position is that running Rayhunter does not violate US law. That is the EFF's reading and ours - it is not legal advice, and if you need certainty, ask a lawyer.

Does it record my phone calls?

No. It never touches call or data content. It reads the signalling conversation between the device and the tower, which is a separate layer entirely.

What do I actually do when the bar goes red?

Treat it as a prompt, not a verdict. Note the time and where you were, leave the area if that is warranted, and keep the capture. The EFF accepts PCAPs for its cell-site-simulator research, and we will help you pull the file off the device.

Will it catch every IMSI catcher?

No, and we will not claim otherwise. It detects specific signalling behaviours. Something that does not exhibit those behaviours will not trip it, and a clean reading is not proof nothing was there.

Why is it built on a used hotspot instead of new hardware?

Because that is the hardware the firmware supports. The device was carrier-subsidised and is no longer sold new, so the supply is secondhand by necessity. We buy, flash, bench-test, and verify each unit rather than shipping you an eBay gamble.

NEXT STEP

Talk to us before you buy a detector

Tell us what you are actually worried about. Half the time the honest answer is a different device, or none of them.

Request a Site Assessment Call (304) 555-0142