How Find My Locates Erased iPhones on iOS 15

With the release of iOS 15, Apple introduced the ability to track an iPhone via the Find My network even after the device has been erased or factory reset. This system functions through a combination of persistent Activation Lock, low-power hardware beaconing, and Apple's massive crowdsourced mesh network. As long as Activation Lock remains enabled, the wiped device continues to emit encrypted Bluetooth signals that nearby Apple devices detect and securely relay to the owner, ensuring a lost or stolen phone can still be recovered.

Persistent Activation Lock

Prior to iOS 15, erasing a device locally or remotely removed it from the active Find My map, even though Activation Lock prevented unauthorized reactivation. In iOS 15, Apple separated device erasure from Find My tracking. When an iPhone is wiped, Activation Lock remains strictly bound to the owner's Apple ID. During the initial setup ("Hello") screen, the system displays a persistent notification stating that the iPhone is locked to an owner and remains locateable.

Low-Power Bluetooth Beaconing

The technical foundation of this feature relies on low-power hardware reserve states available on iPhone 11 and later models. When an iPhone running iOS 15 is wiped or powered down, specific chips—such as the Bluetooth controller, the Secure Element, and the power management unit—remain partially energized.

Even without an active operating system running user data, the hardware continues to broadcast short-range Bluetooth Low Energy (BLE) signals at regular intervals. These broadcasts consist of rotating, public cryptographic keys derived from the owner's Apple ID.

The Crowdsourced Find My Mesh Network

Once the erased iPhone transmits its BLE beacon, nearby Apple devices (including iPhones, iPads, and Macs owned by strangers) automatically pick up the signal.

  1. Passive Detection: A passing Apple device detects the Bluetooth beacon emitted by the erased phone.
  2. Location Tagging: The detecting device notes its own current GPS coordinates.
  3. Encrypted Relay: The detecting device bundles its location with the received beacon payload and uploads it to Apple’s cloud servers over an encrypted connection.

This entire process occurs silently in the background, consuming minimal battery and data on the relaying devices.

End-to-End Encryption and Privacy

Apple designed the Find My network using zero-knowledge, end-to-end encryption to preserve user privacy:

  • Relay Anonymity: The owners of the intermediate devices that relay the signal cannot see which device they detected or where it belongs.
  • Apple's Blindness: Apple receives the encrypted location package, but lacks the private cryptographic key required to decrypt the coordinates.
  • Owner-Only Decryption: Only the original owner, logged into their Apple ID on another trusted device, possesses the private key. When the owner opens the Find My app, their device downloads the encrypted location packets from Apple and decrypts the coordinates locally to plot the erased iPhone's location on the map.