TacLink has one rule about signal: you need it to join an event, and you do not need it to play. This post explains why the line sits there.
What happens at join
When you scan your side’s QR code, the app asks the server to add you to the event. The server checks the player cap, puts you on that side, places you in a squad, and sends back the event bundle. The bundle holds everything the live map needs: the brief, the area, the sides and squads, the pins and their icons, the organizer’s map image, and a key for your side’s mesh. The app also downloads the base map tiles for the event area.
All of that is a single exchange with the server, and it happens before the game starts.
Why not join offline
An earlier version let a phone host an event with no server at all. It worked, and it was the part people understood least. It needed its own rules for who could host, who could join and who had paid. The playtest showed that the extra paths cost more in confusion than they gave in coverage.
There is also a simpler reason. Meeting points almost always have signal: car parks, field entrances, the safe zone. Players arrive there, check in, chrono their guns and listen to the briefing. That is the natural moment to join, and the phone has signal at that moment.
What happens during the game
Once you have joined, the live map does not need the network. Phones on the same side that are near each other exchange positions, enemy markers, squad pins, player status and orders over Bluetooth. The data is encrypted with the side’s key from the bundle, so the other side cannot read it.
If one phone on your side has signal, it works as a bridge. It sends the side’s mesh picture to the server and brings back positions from the rest of the side. Markers and acknowledgements made with no signal wait on the phone and sync when signal returns.
The mesh covers squad range: tens of metres per hop, with phones relaying for each other. It does not cover a whole large field on its own. Mesh range extenders for longer distances are coming soon.
What this means for organizers
Put the meeting point where there is signal and have players scan their side’s QR code there, before they walk to the start positions. If the field has no signal at all, the game still runs, because joining is already done.