If you spend time beyond reliable cell coverage, "off-grid communication" is the term for keeping a group in touch without a carrier. Nelos is a modern app built for exactly this: connect your phone to a small radio, and your group gets messaging, everyone's location on a worldwide offline map, device trackers, location history and a Need Help button.
Most of the time, "communication" and "the mobile network" are the same thing - you send a message and it arrives, and you never think about how. Off-grid communication is what you fall back on when that network isn't there: a way for a group to message each other and share where they are, using equipment the group carries rather than infrastructure someone else runs. Nelos is a finished, actively maintained app for exactly this - not a technical project - and you can start using it for free.
Off-grid communication is any method of exchanging messages, voice, or location that does not rely on cell towers, Wi-Fi, or an internet connection. "Off-grid" here means off the communication grid - it has nothing to do with solar panels or living off the electricity grid, though the same trips and places often involve both.
The key distinction is who runs the network. A mobile network is built and maintained by a carrier: your phone talks to the nearest tower, the carrier's infrastructure carries the data, and it comes out at the other end. You rent access to that chain through a plan. Off-grid methods replace that chain with something small and local - two handheld radios talking directly, a group of radios linked directly or through repeaters, or a link straight up to a satellite - so the group stays in contact in places where no carrier has built anything.
That independence is the whole point, and it's also the limit. Because an off-grid network is just the group's own devices, it keeps the group in touch with each other - but most methods can't reach anyone outside the group, and can't dial an emergency number. Knowing which methods can reach out and which can't is the single most important thing to get right.
A common point of confusion: you lose signal, your map app still shows a blue dot exactly where you're standing, but a location you shared with family at home stops updating. Both things are true at once, because they're two different systems.
GPS (and the other satellite positioning systems grouped under the term GNSS) is receive-only. Satellites broadcast their time and position continuously; your phone listens to several of them and works out where it is. It transmits nothing, needs no SIM, and doesn't care whether there's a tower nearby. So your phone almost always still knows its own location off-grid.
Sending that location to someone else is a separate step that needs a data path - and that path is exactly what disappears when you leave coverage. This is why apps like Life360 and Find My freeze: the phone still has the coordinates, but nothing to send them over. The guides does GPS work without cell service and does Life360 work without signal go through this in detail. Off-grid communication is about providing that missing data path.
There is no single best method - each one does part of the job well and barely touches the rest. The honest comparison (the guide how to text without cell service focuses specifically on the messaging side of this list):
Handheld walkie-talkies give instant voice when the group is close. Push a button, talk, and anyone on the same channel hears you right away - no pairing, no app, low cost. The trade-offs: it's a live conversation, not a stored message, so anyone not listening at that moment misses it; there's no map or history; and range collapses with terrain - one ridge between two radios can cut the link. Best for a small group staying within sight or shouting distance in open country. Whether a walkie-talkie or a LoRa mesh system fits your group is weighed directly in LoRa mesh vs walkie-talkie.
Each person carries a small low-power radio, usually paired to a phone. The radios send short text and location coordinates directly to each other, and - this is the "mesh" part - a repeater, or a radio switched to Companion Repeater mode (which uses more battery), can relay messages so the group doesn't all need to be in direct range. No subscription, no account, no towers. The trade-offs: it's slow (fine for messages and location, not photos or voice), range still depends heavily on terrain, and it only reaches the group - not emergency services. See what a LoRa mesh radio is and how LoRa mesh compares to a cellular network.
Handheld satellite messengers (Garmin inReach, Zoleo, and similar) and the satellite texting on some newer phones connect straight to an orbiting network instead of a ground tower. Crucially, they reach outside the group - a relative in another region, or an emergency coordination centre via an SOS button - from places with no infrastructure at all. The trade-offs: a monthly subscription, a higher device cost, a slower messaging pace, and the need for a fairly clear view of the sky. Not a way for a whole group to chat all day, but the right tool for reaching help. The guide LoRa mesh vs satellite messenger weighs the two side by side.
Some apps can pass messages directly between phones that are very close together, with no extra hardware. Useful in a dense crowd where the network is overloaded rather than absent, but the range is only tens of metres and it depends on everyone running the same app. Not a solution for a group spread across a trail or a campsite.
A personal locator beacon (PLB) does one thing: when activated, it broadcasts your identity and location to a government search-and-rescue network. No messaging, no subscription, no check-ins - just a distress signal. It's a last-resort safety device that sits alongside the methods above, not a way to communicate day to day.
The smartphone-plus-radio model is worth understanding on its own, because it's the approach that feels most like the messaging apps people already use. The mental model is a chain:
Phone → Bluetooth → LoRa radio → mesh → LoRa radio → Bluetooth → Phone
Your phone stays the part you look at and touch. It provides the interface, the message history, the group and contact management, the maps, and - through its own GNSS receiver - your location. The radio does one job the phone can't: it carries that data over the air when there's no cellular network, talking directly to the other radios in the group.
Because the phone and radio are joined only by Bluetooth - like wireless earbuds - the phone can stay in a pocket or a pack while the radio sits higher up or outside a vehicle for a better signal. And because the maps are downloaded to the phone in advance, you still get a full map with everyone's latest position on it, with no connection of any kind.
The catch is that both pieces have to be working: a charged phone with the app and offline maps, and a charged, paired radio. Lose either and you're back to voice-range-only or nothing.
The radio also runs a network protocol that turns a set of separate radios into one network, with repeaters doing the relaying - Nelos handles this for you, so you never have to configure it directly. A compatible tracker with GPS can join the same network without a phone attached at all - see GPS tracker without a SIM card for how that works.
A mesh network flips the usual model. Instead of every device talking to one big tower, the devices talk to each other directly, and a message can hop through repeaters to reach someone further away. A few consequences follow from that:
The guide how reliable a mesh network is in the field covers what to actually expect - including the fact that people walking behind a ridge drop out and reconnect a few minutes later, which is normal for a network you carry rather than a fault.
Most groups end up combining methods: an internet app where there's coverage, a local layer for the stretch with none, and - if the trip warrants it - a satellite device for emergencies. A rough guide by situation:
If you used goTenna Mesh and are looking for where to go next, goTenna Mesh alternatives compares the current options directly.
One thing that separates the methods commercially: two-way radios and LoRa mesh have no recurring fee, because nothing you send goes through a company's network. Satellite messengers almost always carry a monthly or annual plan, because every message uses a satellite operator's capacity.
For a group that mostly needs to stay coordinated - not send an SOS - a no-subscription local method covers the common case at a one-time hardware cost, and a satellite device can be added later as a separate safety layer only if the trips call for it. It's worth being clear about which problem you're actually solving before paying for a plan.
Nelos is a smartphone app for the group-communication part of this picture. It runs on top of compatible LoRa mesh radios: you pair a radio to your phone over Bluetooth, create a private group, and get messaging, everyone's latest location on a worldwide offline map, device trackers for people or gear, and a "Need Help" button that alerts your group. There's no account, no subscription, and no central server - the group's messages and locations travel only over the group's own devices.
Nelos is not a satellite messenger and not a rescue device. It's the layer that keeps a family or group in touch with each other when the carrier network isn't there. If that's the problem you're solving, the next steps are choosing hardware and setting up a group:
Off-grid communication devices walks through the handhelds, trackers, and repeaters that work with Nelos; Getting Started covers pairing a device and creating a group; and the app itself is a free download for iPhone and Android.
Nelos brings group messaging, location sharing, and a shared group map with location updates to LoRa mesh — with no cell service, no server, and no account.
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