Cell Site Simulator Detector: Apps, Android 16 Alerts and Rayhunter Compared

Which cell site simulator detector works? Android 16 network alerts, EFF's Rayhunter, detector apps and SDR scanners compared, and what none of them can catch.

Short answer: there is no consumer cell site simulator detector that gives proof. The two most credible options in 2026 are Android 16's built-in network notifications (on phones with the right modem, currently Pixel 10 models) and EFF's open-source Rayhunter. Apps are hit-and-miss, and research-grade scanners need radio skills. This guide compares them. For background on how stingrays work and the warrant rules, see our explainer on how to detect a stingray device.

What a detector is actually looking for

Active cell-site simulators leave traces in network signaling. EFF's 2019 white paper and Rayhunter's documentation list the main red flags: a forced downgrade to 2G, a tower requesting your phone's IMSI or IMEI and then skipping authentication, missing or odd broadcast messages, a "null cipher" (no encryption), and towers that appear briefly and vanish. Every one of these has innocent explanations too, which is why every tool below gives indicators, not verdicts.

Option 1: Android 16 network notifications

Google's Android Open Source Project documentation describes a Mobile network security section in Android 16's Safety Center. It has two parts:

Network notifications: alerts when the phone connects to an unencrypted network, reconnects to an encrypted one, or exchanges identifiers such as IMSI or IMEI with the network. The toggle is off by default.
2G network protection: turns off 2G, also off by default.

The catch is hardware. The notifications require a modem supporting version 3.0 of Android's IRadio interface. Android Authority and Android Police reported that existing Pixels, including the Pixel 9 series, do not show the page; reporting in 2026 says the Pixel 10 series supports it. Google's own documentation warns that "normal use of the device is also associated with limited or infrequent exchange of device identifiers," so one alert means little. Frequent alerts in one place are more interesting.

How to turn it on (supported phones): Settings > Security & privacy > More security & privacy > Mobile network security, then enable Network notifications and 2G protection.

Option 2: EFF Rayhunter

EFF released Rayhunter on March 4, 2025. It runs on an inexpensive mobile hotspot, originally the Orbic RC400L, with community support for some other devices. It reads the hotspot's cellular control traffic and shows a warning when its heuristics fire, such as IMSI requests followed by no authentication, 2G downgrades and incomplete broadcast messages. It is free and open source. EFF asks users who get alerts to save the logs and share them.

Strengths: works regardless of what phone you carry, logs evidence, transparent code. Weaknesses: one more device to carry and charge, setup takes some technical comfort, and EFF says results can include false positives.

Option 3: Detector apps

Apps such as SnoopSnitch and AIMSICD were early attempts. EFF's white paper found that detector apps vary in quality, apply different heuristics and can reach different conclusions about the same tower. Several need rooted Android phones or specific chipsets, and some are no longer maintained. Use them as a curiosity, not a safeguard.

Option 4: SDR scanners

Researchers have used software-defined radios to map anomalies across whole cities over time: the University of Washington's SeaGlass project and EFF's Crocodile Hunter are the best-known examples. This is the most rigorous approach because it builds a baseline of what "normal" towers look like. It also requires radio hardware, Linux skills and a lot of time.

Comparison at a glance

Android 16 alerts: no extra device; limited to supported phones; off by default.
Rayhunter: best consumer option for evidence logging; extra hardware.
Apps: easy to install; least reliable.
SDR: most rigorous; expert-only.

What no detector can do

None of these can catch a passive IMSI catcher, which only listens. EFF says it is impossible for anyone to know whether a passive IMSI catcher has accessed their phone. No detector can tell you who ran a device, whether you were the target, or what your carrier handed over under a court order. Protection still comes from habits: disable 2G where you can, use end-to-end encrypted apps like Signal, and stop transmitting when it matters with airplane mode or a tested signal-blocking pouch (see how to test a Faraday bag). Our store carries preparedness and communications gear for that last step.

Documented vs opinion

Documented: the features, requirements and limits above come from Google's AOSP documentation, EFF and the cited tech press. Our opinion: Google putting stingray warnings into the operating system is the most important change in years, because it moves detection from hobbyists to ordinary users. It will matter only once supported hardware is common, and only if people turn it on.

Sources

Android Open Source Project, Mobile network security: source.android.com
Android Authority, Android 16 fake cell tower warnings (June 2025): www.androidauthority.com
Android Police, Android 16 anti-stingray settings: www.androidpolice.com
WIRED, Android may warn about fake cell towers: www.wired.com
EFF, Meet Rayhunter (March 2025): www.eff.org
Rayhunter heuristics: efforg.github.io
EFF IMSI catcher white paper (2019, PDF): www.eff.org
EFF Street-Level Surveillance, cell-site simulators: sls.eff.org

Frequently asked questions

What is the best cell site simulator detector?

For most people, EFF's free Rayhunter on a supported hotspot, or Android 16's built-in network notifications on a phone with compatible hardware (currently the Pixel 10 series). Neither proves a fake tower; both flag suspicious behavior.

Does Android warn about fake cell towers?

Android 16 adds a Mobile network security page with network notifications for unencrypted connections and identifier (IMSI/IMEI) requests. It needs modem support for IRadio 3.0, is off by default, and Google's docs note normal networks also request identifiers sometimes.

Do iPhones detect stingrays?

Apple does not offer a stingray alert. Lockdown Mode disables 2G support, which removes a common downgrade path, but it does not warn you.

Are stingray detector apps reliable?

EFF's 2019 research found popular apps implement different checks, often disagree and in some cases are unmaintained. Treat app alerts as weak signals.

Can any detector catch passive IMSI catchers?

No. Passive catchers only listen. EFF says it is impossible for anyone to know whether a passive IMSI catcher has accessed their phone.