https://en.wikipedia.org/wiki/Bluetooth https://en.wikipedia.org/wiki/Bluetooth In the most widely used mode, transmission power is limited to 2.5 milliwatts,

https://en.wikipedia.org/wiki/Bluetooth https://en.wikipedia.org/wiki/Bluetooth In the most widely used mode, transmission power is limited to 2.5 milliwatts, giving it a very short range of up to 10 meters (30 feet). If I read correctly a cell phone is using more like 1-2W so 800 times as strong. One could also use something, the horror, with a wire!