Citizen
No menus, no login. It keeps broadcasting even if the phone is buried or the person is unconscious. It shows one line: “3 devices carried your signal.”
Post-disaster communication blackout
The network is gone. Phones still talk.
When towers fall and the internet dies, Zone phones pass a tiny distress signal from hand to hand over Bluetooth, until it walks out of the disaster zone in someone's pocket.
And when a whole cluster of phones goes quiet at once, Zone tells you exactly when, and where.
Android: tap the downloaded file and allow “install from this source” once.
One phone · heartbeatMissed 3 in a row
Silence is the signal. Every packet says when the phone will speak next. When it doesn't, we know something happened, and when.
One app, three roles
Pick your role once. The app does the rest.
Responder
A ranked list of who has been heard, and a Dig Here bar that fills as you get closer. Built for one hand and gloves.
Map
A severity grid showing which areas are hit hard and which went completely dark, with the minute it happened.
Swipe for the next role →
What changes
The problems it takes off the table
Trapped people can’t call for help. No signal.
Their phone reports itself, hands-free.
Rescuers don’t know where survivors are.
A live list builds at the perimeter.
Can’t tell a roof from a basement.
The barometer gives height to ±1–2 m, where GPS is dead.
Reports are fragmented and contradictory.
One panicking phone is a ghost; three that agree are a signal.
Phones die in hours.
Battery-aware: days of honest heartbeats.
The one nobody else has
Can’t tell a flattened village from a flooded one.
CELL_LOSS: a cluster that goes silent together means the area was destroyed, at a known minute.
Why nobody else has this
Chat apps can’t notice silence. Zone is built on it.
Every packet declares when the device will next transmit. A phone at 70% battery that promised to speak in ten seconds and vanished at three has had something happen to it, and we know within one interval when. A dying battery is expected. This is not.
Bridgefy, Briar and goTenna are messaging apps. Messaging has no idea of an expected next message. Zone is structured telemetry, so the differentiator and the architecture are the same decision.
Known limits
Stated, not hidden
iPhone can’t join the mesh
Apple restricts Bluetooth advertising. A real deployment needs an entitlement or a cheap hardware beacon. Today it is Android only.
Bluetooth doesn’t pass through rubble well
We don’t pretend otherwise. A pinned phone keeps advertising for days at low power, and a rescuer walking the pile eventually gets within about 10 m. That turns “search this block” into “search this circle.”
Long-range mode depends on the phone’s chip
Coded-PHY support doesn’t track price or release year. So the radio runs dual-mode and falls back to standard Bluetooth where long range is missing.
The last mile is out of scope
The responder’s phone is the gateway. Even if it never syncs, “47 signals in this building, 3 marked rising water” is already the whole product.