Which radios a phone can use
A modern phone carries several radios, but only some of them can link one phone to another with no infrastructure.
- Bluetooth Low Energy (BLE). Every current iPhone and Android phone has it, and both platforms let apps advertise, scan, and connect: Core Bluetooth on iOS, the Bluetooth LE APIs on Android. It is the one radio that works phone to phone on both platforms, which makes it the usual base for a phone mesh.
- Wi-Fi peer-to-peer. Android supports Wi-Fi Direct and, on some hardware, Wi-Fi Aware. Apple offers Multipeer Connectivity, which uses Wi-Fi and Bluetooth underneath, and since iOS 26 a Wi-Fi Aware framework for pairing with Wi-Fi Aware devices. Wi-Fi Direct and Multipeer Connectivity are platform-specific: an iPhone and an Android phone cannot connect to each other with them. Wi-Fi Aware is a Wi-Fi Alliance standard on both, but iPhone pairing goes through Apple’s own pairing interfaces.
- Cellular and satellite. Both depend on an operator’s network, and phones do not give apps a direct phone-to-phone mode over them.
- NFC. Works only over a few centimetres. Useful for a tap, not for a network.
What the software has to add
The radio provides a link between two phones. Everything that turns links into a network is software, usually a library inside the app:
- Discovery. Advertise this phone’s presence and scan for others, continuously, because people move.
- Connections. Open links to nearby phones and notice when they drop.
- Routing. Pass messages on for others, with a hop limit and duplicate suppression so they do not circle.
- Holding messages. Keep a message when no path exists yet, and retry when one appears.
- Encryption and identity. Encrypt end to end so relays carry content they cannot read, and let each phone prove who it is with a key it holds.
Phones running the same app can then reach each other across the group, even when two of them are never in range directly.
The platform limits
Phone operating systems protect battery and privacy, and both shape what a phone mesh can do.
Background rules. iOS lets an app use Bluetooth in the background only if it declares the right background modes, and even then behaves differently: Apple documents that, in the background, repeated discoveries of a device are coalesced into one, scanning can happen less often, and an app’s advertisements leave out its local name and move its service identifiers to an overflow area. Android has its own limits on background work and battery optimisation, and since Android 12 it asks the user for separate Bluetooth permissions to scan, advertise, and connect.
Range. The Bluetooth SIG says the effective range between Bluetooth devices runs from more than a kilometre down to less than a metre, depending on the radio, transmit power, antennas, and what is in the way. Phones have small antennas, and bodies and walls absorb signal, so phone-to-phone links indoors sit well short of the best case. A mesh extends reach by hopping, not by making any single link longer.
Throughput and battery. BLE suits messages, small documents, and status updates far better than video. Scanning and relaying cost power, so a phone mesh has to balance how often it listens against how long the battery lasts.
What a phone mesh is not
A mesh built inside an app is usually its own protocol on top of BLE. It is not the Bluetooth SIG’s Bluetooth Mesh standard, so it will not talk to Bluetooth Mesh lights and sensors unless it implements that specification too.
It is also not internet access. Phones in a mesh can reach each other, but they reach the internet only through a device that has a connection and is set up to act as a gateway.
Where phone meshes are used
Phone meshes help wherever people are close together but the network is missing or overloaded: crowded stadiums and festivals where cells saturate, disaster areas where towers lose power, ships and remote sites with no coverage, and field teams moving in and out of signal. In each case, the phones that are already there become the network.