What Your Phone Broadcasts (Without Asking Permission)
Every device in your pocket is continuously announcing its presence. MAC addresses, probe requests, Bluetooth beacons, cellular timing — here is exactly what leaks, how far it travels, and what it reveals about you.
Published 2025-02-20
Your phone does not wait to be asked. It announces itself constantly, to anyone listening. Understanding what leaks — and what it actually reveals — is the foundation of any serious privacy practice. This is not a list of hypothetical concerns. These are documented, reproducible behaviours of every modern smartphone. 1. Wi Fi Probe Requests When your phone is not connected to a Wi Fi network (and often when it is), it broadcasts probe requests — asking "is [network name] available?" for every network in its saved list. Until 2014, these probe requests included your real MAC address — a hardware identifier unique to your device. Anyone with a passive Wi Fi receiver could log your presence, movement, and timing with sub metre accuracy across any space with listeners. Modern iOS (since iOS 14) and Android (since Android 10) randomise the MAC address used in probe requests. This is a genuine improvement. It is not complete protection: Randomisation is often disabled when connecting to saved networks Some manufacturers implement it incorrectly Timing patterns, probe request content, and device capability fingerprints remain unique even with randomised MACs Researchers at the University of Hamburg (2021) found that 40% of Android devices leaked their real MAC address in probe requests despite having randomisation enabled, due to implementation bugs in specific chipset drivers. 2. Bluetooth Beacons Bluetooth Low Energy (BLE) devices broadcast advertisement packets continuously — approximately every 100–1000 ms depending on configuration. These packets include: A device address…
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If any of this frightens you: this site documents what signal physics makes possible in a laboratory, which is not evidence about what is happening to any individual. If you feel watched, targeted or unsafe, that distress is real and treatable. Read about paranoia, mental health and how to get help, or call a free 24/7 line — 988 in the US and Canada, 116 123 in the UK and Norway, 13 11 14 in Australia, or find your country at findahelpline.com.