Discover & understand

(Re)take control of our communications

Our everyday tools (Signal, WhatsApp, Telegram) depend on the Internet, commercial mobile networks (4G/5G), and central servers. In case of increased surveillance, those networks can be compromised and your data collected.

Even for someone standing right next to you, a WhatsApp or Signal message usually travels over 4G or Wi‑Fi, through your mobile operator (who is also your ISP on the cellular network), then across an ocean to a remote server (often in the United States) before coming back to the recipient. Your IP address (and in practice your civil identity and communication habits) can be known at every step and under several jurisdictions, while your phones are only metres apart.

By contrast, a radio message on a mesh network mostly follows a path close to the real distance between correspondents: from repeater to repeater, in the neighbourhood. No information tied to your civil identity is sent to operators, ISPs, or platforms: no IP address, no account linked to a phone number or email address. MeshCore offers another path: connect a radio device over Bluetooth to your phone to exchange text messages by radio; you can even remove your SIM card or leave aeroplane mode on. Exchanges are text only: no voice calls, photos, or video. You reduce your dependence on infrastructure controlled and observable by operators, states, and commercial platforms; this is what people call being off-grid (« off the grid »).

Smartphone hygiene, private channels, and field best practices: see the Protect page.

LoRa, the physical engine

LoRa is a low-power radio technology, invented in France (startup Cycleo, Grenoble) before being acquired by Semtech. In Europe it uses the 868 MHz band: free, unlicensed frequencies, no operator subscription, and the ability to build your own radio devices without an amateur radio licence, provided you respect legal limits (power, airtime).

Software-defined radio (SDR)

SDR (software-defined radio) means a chip or computer replaces the fixed radio hardware of the past. In practice MeshCore relies on dedicated LoRa chips in licence-free bands: no operator, no subscription, but power and airtime rules to follow.

MeshCore and the mesh

MeshCore is a decentralised text messaging system designed to work entirely offline. No images, audio, or video: the app encodes your messages into radio signals and sends them across a mesh of radios, without the Internet or an operator. It is the walkie-talkie principle applied to text messaging, with repeaters to extend range.

The protocol was launched in 2025 by two Australian and New Zealand developers, notably to respond to network outages after natural disasters. The code is released under the MIT licence (open source): transparent, auditable, and freely reusable.

The mesh network

Unlike conventional messaging where everything passes through a distant central server, in a mesh network it is repeaters (called repeaters in MeshCore) that carry the message to the recipient when they are not directly in range.

Five ways to exchange messages

All MeshCore interactions go through text messages on LoRa radio: conversations, channels, drop boxes, or sensor readings. Nothing else travels over the air. Unlike online messaging, a radio message only exists while it is being transmitted: it is only readable by people whose radio was switched on and within signal range when it passed through.

The first three modes below are live exchanges between people on this principle. The last two go through a dedicated device on the mesh, reachable like a contact in the app. The room server is the exception: not a volatile channel, but a fixed device that keeps deposited messages for authorised people, including those who were not on the network when they were sent. Telemetry is for remotely querying a sensor deployed in the field.

Device details (companion, repeater, room server, sensors, observers) are in the section A mesh made of nodes.

Visible activity vs protected content

On MeshCore, each radio message has two layers: activity (who is talking, when, via which repeaters, on which channel) and content (the text itself). Radio activity is always detectable; content may be plain text (public channel) or encrypted (private channel, direct message). Encryption protects the letter, not the envelope.

For detail, concrete examples, and diagrams, see Protect and Which mode for what sensitivity.

Identity on MeshCore rests on the encryption key, not the displayed pseudonym, and not on your civil identity. See Protect: Two distinct identities and Protect: your radio identity.

Where does Brussels fit in?

In Brussels, the MeshCore mesh is still in its early days. Other European cities already have denser citizen networks; here, much remains to be built. Every additional repeater therefore counts twice as much.

In Wallonia, communities are following the same movement a few months behind (#liege, #namur…): this guide’s local settings stay anchored in Brussels, but the path is shared.

LoRa radio mostly travels line of sight: in Brussels, brick walls, concrete, slopes, and trees weaken the signal. The city alternates high areas (Saint-Gilles, Forest, Altitude Cent…) and low areas (city centre, Molenbeek…). A few repeaters on the heights often suffice to link the whole area; a message can also skirt a neighbouring district to get around an obstacle. About ten well-placed repeaters would noticeably improve coverage in the centre: that is the local network’s ambition.

In practice, two levers to grow the Brussels mesh:

Cover from the heights

Repeaters placed high on the rim of the Senne valley (Saint-Josse, Saint-Gilles, Ixelles) link districts below and strengthen the mesh for the whole neighbourhood. That is the collective ambition of the local network; see Build the mesh for installation.

Map poorly covered areas

With equipped friends, test on outings where messages get through or stop. Gradually you identify districts and streets still poorly covered, especially in the centre, and you know where the next repeater will help most.

A mesh made of nodes

In a mesh network like MeshCore, every device connected to the network is called a node. A node is a point on the mesh: by relaying messages, nodes collectively make up the network.

On MeshCore, each node is assigned a fixed role. In theory, any compatible device can be configured for any role; in practice, how it was designed makes it better suited to some roles and less to others.

For most participants, two roles are enough. Here is how they are named in MeshCore and how they match the vocabulary used earlier in this guide:

The two essential roles

Ideal starter setup in the city

In Brussels, the most accessible combination today remains a window- or balcony-mounted repeater and a companion to communicate: expect a few dozen euros for the pair.

Placed outside, the repeater brings messages into the flat and maximises your chances of being reachable, even if the companion stays at the bottom of a bag. The companion goes with you when you leave. Once city coverage is sufficient, a companion alone will be enough to join the network.

Ethics and community

At the time of writing (2026), MeshCore remains a young protocol in constant evolution. Using this system means accepting some instability and occasionally updating node firmware (companion or repeater) via the MeshCore Flasher.

In a decentralised network, responsibility is shared. If you unplug a repeater or install it poorly (bad location, unsuitable settings), neighbourhood coverage weakens for everyone. Turning off your companion, on the other hand, only affects your own reachability.

Technical anonymity and radio background noise: see Protect.

Saturation and duty cycle

In a dense area, a shared LoRa network can saturate if too many nodes transmit in bursts or if ancillary uses such as ill-timed telemetry monopolise bandwidth.

Although ISM regulation and MeshCore settings provide for a duty cycle, compliance is not automatically guaranteed on every node on the mesh: it is a collective discipline, not a technical guarantee. Saturating the network is like holding the push-to-talk button on a walkie-talkie: others cannot transmit. By following community-suggested settings, saturation should not be a problem in Brussels.

There is also a risk of sabotaging the network, most often accidental or unconscious: bad settings, misconfigured bots, network-wide adverts too frequent… Because these problems appeared fairly quickly elsewhere, MeshCore developers have already begun building tools to protect the mesh, and the community deploys them gradually through updates and settings. For a companion, updating every 6 to 12 months is enough; on the repeater side, staying aligned matters more. As the network reaches maturity, frequent updates will be less necessary.

MeshCore has a region setting on each device, to limit traffic propagation when the network saturates. Since August 2026, the Flemish #BEmesh community has tightened handling of messages without a region (unscoped), mainly because of coastal traffic from the UK. In Brussels the mesh is still nascent: we prepare the region tree and stay deliberately more flexible, without blocking newcomers. In Wallonia: same region default be, home = province, tree with be-wal; detail and per-area CLI on Build / Catch-up.