Can phones message each other without the internet?

Why it matters: the network can be switched off

Most messages travel through a phone company's towers and a tech company's servers. Either can stop.

On 4 October 2021 Facebook pushed a faulty configuration change. Its routes vanished from the internet, and Facebook, Instagram and WhatsApp went dark for about six hours worldwide (Cloudflare, 2021). In many countries WhatsApp is how families, shops and clinics talk.

Governments switch networks off on purpose too. In 2024 the digital rights group Access Now and its partners counted 296 internet shutdowns in 54 countries, the most on record. Shutdowns cluster around protests, elections, exams and conflict (Access Now, 2025).

How a mesh works

Every phone already carries short-range radios: Bluetooth and Wi-Fi. A mesh app uses them to talk to phones nearby. If the person you want is out of range, your message goes to a phone that is in range, which passes it on, and so on. Each phone is both a sender and a relay.

• Range per hop is short. Bluetooth can reach from under a metre to over a kilometre, depending on the radio, power and what stands in the way. Walls, bodies and metal cut it sharply (Bluetooth SIG, n.d.). With phones in a crowd, think tens of metres.
• It needs people. A mesh works in a packed street or a camp, and thins out fast in a suburb.
• It carries text, not video. Short messages move well. Large files crawl.

The Hong Kong lesson: a mesh is only as safe as its code

In 2019 protesters in Hong Kong downloaded Bridgefy, a Bluetooth mesh messenger, in large numbers. It later spread to protests in India, Iran, the United States, Zimbabwe and Belarus.

Security researchers then took it apart. They found anyone nearby could track users, read messages, impersonate any user, and shut down the whole network with one crafted message (Albrecht et al., 2021). Bridgefy rebuilt its encryption on the Signal protocol. A second study found attackers could still read private messages, and impersonate users in broadcast channels (Albrecht et al., 2022).

The lesson is not "don't use a mesh". It is: a tool used by people at risk must be checked by people outside the company that sells it.

Tools that exist today

Tool	How it connects	Worth knowing
Briar	Bluetooth or local Wi-Fi when offline; the Tor network when online	Free and open source, no central server, no phone number needed. Messages sync directly between devices and are encrypted end to end (Briar Project, n.d.).
Meshtastic	Cheap LoRa radio modules paired to your phone	Free and open source. Radios form their own mesh and reach much further than Bluetooth, running for days on a battery. Encrypted by default. You must buy the radio (Meshtastic, n.d.).
Bridgefy	Bluetooth	Widely used, but see the two studies above before trusting it with anything sensitive.

What a mesh cannot do

• It cannot reach the wider internet unless some phone in the chain has a connection.
• It cannot hide that you are there. A phone that broadcasts announces itself to every radio nearby, including one held by someone watching.
• It cannot help if you install it after the network goes down. You need the app, and your contacts added, beforehand.
• Jamming radio is illegal in most places, but possible.

What to do now

A mesh is a backup, like a torch in the kitchen drawer. It only helps if it is charged, in reach, and you already know how to use it when the lights go out.

1. Pick a tool with published, independent security reviews. Open source helps, because anyone can check it.
2. Install it before you need it, and add the people you would want to reach.
3. Test it once with a friend: phones on flight mode, Bluetooth on, walk apart, and see where it drops.
4. For a household, a bushfire zone or a remote property, look at radio-based meshes such as Meshtastic, which reach further than phones alone.
5. Keep sensitive talk off any mesh you have not checked. Assume people nearby can see that you are sending.