Three phones, one hop online
The sender
Signs on a phone with no signal. The key never leaves it.
The relay
Any phone nearby. Passes the bytes on and never reads them.
The gateway
Whoever has signal. Broadcasts, then sends a receipt back.
One phone alone signs and waits. Two phones in a room can pay. A dozen across a building is a network.
What travels
The chain does not care how the bytes arrived, only that they are valid and inside the window.
When a send does nothing
You were the only node. The payment waits on your phone and goes the moment a neighbour appears or you come back online.
Testing needs two phones. The test guide sets that up.
Where the range ends
Bluetooth reaches about thirty metres in the open, less through walls. The same 139 bytes fit one LoRa packet and one text message, which is where the roadmap goes next.