Phone Tracking: What a Faraday Bag Blocks (and What It Doesn't)

Turning a phone off is not the same as making it unfindable, and airplane mode isn't either. This page sets out what actually keeps transmitting, what a Faraday bag genuinely stops, and — just as important — the things it does nothing about. We sell Faraday bags; the sourcing here is Apple's own documentation rather than our claims.

A Powered-Off iPhone Can Still Be Located

This surprises most people. Per Apple's Find My documentation, with the Find My network enabled you can locate a supported iPhone for up to 24 hours after it has been turned off, or up to 5 hours when it's in power reserve mode. Apple also notes that when the battery becomes critically low, the device's location is sent automatically.

The mechanism is a low-power Bluetooth beacon that keeps advertising after shutdown; nearby Apple devices relay that sighting. It's a genuinely useful anti-theft feature — and also the reason "I switched it off" is not a privacy guarantee. Apple provides an opt-out per shutdown: on the power-off screen, tap iPhone Findable After Power Off.

Airplane Mode Is Not Off Either

GPS keeps working. GPS is receive-only — your phone listens to satellites and needs no network to work out where it is. Airplane mode doesn't stop the phone knowing its position; it stops it sending it over the mobile network.
Wi-Fi and Bluetooth can be switched back on independently while airplane mode stays enabled, and phones often remember that state next time.
Wi-Fi and Bluetooth scanning can still contribute to approximate location.

What a Faraday Bag Actually Stops

A sealed Faraday bag attacks the one thing all of the above depend on: radio getting in or out.

Cellular — no tower connection, so no network-side location and no calls or data.
Wi-Fi — no joining or scanning networks.
Bluetooth — including the powered-off Find My beacon above, and any nearby-device relay.
GPS reception — satellite signals don't reach the phone, so it can't compute a position while sealed.

You can verify all of it in 30 seconds: seal the phone, call it from another phone. No ring means nothing is getting through. Try locating it in Find My while it's sealed, too.

What a Faraday Bag Does Not Do

This is the part worth being blunt about:

It does not defeat software. Spyware on the device can record location, audio or activity locally while the phone is sealed, then upload it the moment you take the phone out. Shielding is a radio control, not a malware control. If you suspect a compromised device, a bag is not the answer.
It does not erase what's already been sent or stored. Location history in your account, and data already uploaded, are unaffected.
Protection lasts exactly as long as the phone stays sealed. Take it out and it reconnects within seconds — and typically reports its position immediately.
It does not make you anonymous. Your accounts, logins and payment trails are untouched by a fabric pouch.

When This Is Genuinely Worth It

Meetings and conversations where you want certainty that nothing is transmitting.
Focus and digital detox — the phone is genuinely unreachable, not just muted.
Travel and border crossings, where you want a hard, physical off-switch rather than a software toggle.
Suspected trackers — sealing a device stops it reporting while you work out what to do with it.
Chain of custody — the reason digital-forensics teams have used shielded enclosures for years: an isolated device can't be wiped remotely.

If none of those describe you, you probably don't need one — and we'd rather say so. If they do, see our phone Faraday bags or use the Bag Finder.

Using This Page

Journalists and editors are welcome to cite this — please credit Apple Support for the Find My figures and link to their documentation.

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