Some technical details
I assume that you already know what TETRA is, so I just want to tell something about the network parameters.
The used frequency range for the BOS in Europe is 380-400 MHz; at the moment 380.0125 - 384.9875 and 390.0125 - 394.9875 are assigned in Germany. Channel spacing is 25 KHz, beginning on the odd frequencies (380.0125 and so on). Duplex spacing is 10 MHz, uplink on the 38x MHz frequencies, downlink on 39x MHz.
Here some details about a few networks: (A friend tested this out with a professional radio tester)
MCC 262 MNC 5519: Field test network in Aachen, no encryption
MCC 262 MNC 1000: The new German BOS network, already on air in six areas, encrypted
MCC 232 MNC 1000: The Austrian BOS network, in regular use, encrypted