Cell networks fail during disasters in a predictable order. Water finds the equipment shelters and the fiber ducts. Fire takes the masts. Wind takes the power. Each site has a battery for exactly this, and those batteries measure their reserve in hours. When they run out, or when the fiber carrying traffic to the rest of the network is cut, the phones in the area go from full bars to full bars and no service. The display still says you have coverage. There is nothing behind it.
What survives this is the phones themselves. A charged phone with its radio intact can still talk to the phone next to it, directly, without asking any tower for permission. That leftover capability is what Nearby is built on.
Nearby turns nearby phones into a small messaging network that needs no towers. Text messages hop from phone to phone over Bluetooth, up to 7 hops, so people in the same neighborhood can coordinate even when the internet is gone. Relaying phones only carry sealed packets they cannot read.
Street-scale coordination
The communication that matters in the first hours of a flood or a wildfire is rarely long-distance. It is between people who can see the same river, the same smoke, the same blocked road. Is the underpass passable? Does anyone on this street have a pump? Grandmother on the third floor says she is staying, who is with her? The answers matter most to the people within a few hundred meters, which is exactly the distance a Bluetooth mesh covers well.
Nearby has two ways to carry this. Private chats are end-to-end encrypted with a post-quantum handshake (X25519 + ML-KEM-768, AES-256-GCM-SIV) and relayed in sealed packets of one fixed size, so the phones passing a message along learn neither its sender nor its recipient. The public channel, "Everyone nearby", is open to every beChat phone in the mesh. It is the right place for what the whole street needs to know and the wrong place for anything you would not shout out a window. The app says as much when you use it.
Nearby works while other infrastructure does not. It needs no server, and there is nothing for a database to remember: every phone gets a fresh identity each time you turn Nearby on, and turning it off wipes the identity and all messages. After the water recedes, the conversation does not exist anywhere.
Honest limits, because they matter here
- Scale is a street, not a city. Each hop is Bluetooth range. Seven hops is a neighborhood if enough beChat phones stand between here and there, and nothing at all across an evacuated area.
- Everyone needs the app in advance. App stores need the very network that is down. Part of disaster prep is having the tools already installed.
- It carries text only. Photos and calls do not travel the mesh. Keep messages short; the mesh relays them faster.
- Batteries are the clock. Relaying for neighbors uses extra charge. In an outage, a power bank matters more than a full battery at breakfast.
- Strangers can claim any name. The app marks unverified peers as "Not verified" and lets you compare verification codes in person. In a disaster, when requests for help travel these channels, that check is worth the thirty seconds.
- This is not an emergency channel. Nearby cannot reach emergency services or anyone outside the mesh. If someone in the mesh reaches a working network, the call to 112 or 911 happens on that network, with the mesh's news in hand.
Why no history is also a safety property
Disasters make people say things they would only say to someone standing next to them: who has insulin in the fridge, which door is unlocked, who has left and who has not. A record of that, sitting on a server, is one more thing that can leak later or get subpoenaed. Nearby's answer is to keep the conversation in the memory of the phones that took part and erase it when the mode switches off. The default for speech under stress should be that it dissipates.
Frequently asked questions
What happens to cell networks during a natural disaster?
They fail in a predictable order. Floods drown equipment and cut the fiber lines that carry traffic between towers. Wildfires burn the sites themselves. Earthquakes topple masts and sever backhaul. Storms take out grid power, and the batteries that keep a tower alive during an outage last for hours, not days. After that, a phone in the affected area shows full bars and connects to nothing.
How do you communicate when cell towers are down?
Over a path that does not involve a tower. beChat Nearby sends text messages over Bluetooth, phone to phone, relaying through other beChat phones up to 7 hops. Two phones across the street from each other can trade messages with no infrastructure at all, and a chain of phones can carry a message across a neighborhood. Private chats are end-to-end encrypted; there is also a public channel open to every beChat phone in range.
Does beChat Nearby work during a power outage?
Yes. Nearby needs no network infrastructure, only phones with charge and Bluetooth on. The limit is batteries, not connectivity: phones outlast the cell network in an outage, but they do not outlast it forever. A charged power bank is worth more than a full phone.
Does Nearby store my messages on a server?
No. Nearby never touches the beChat server. Messages live in the memory of the phones in the mesh, relayed through sealed packets of a fixed size that hide the sender and the recipient, and everything is wiped when Nearby is turned off. There is no history sitting somewhere that could leak, be seized, or outlive the emergency.
Keep reading
Nearby also fits lighter versions of the same problem: festivals, where the network is overloaded rather than broken, and accidents, where a split group needs one thread of contact. The technical description is on the features page, and beChat is free on Android.