Sepura is a maker of TETRA digital radios, and its handsets are widely used on Germany's BOS network, the shared digital radio system for police, fire services and other emergency organisations. The Ende signal is the short tone that follows a finished transmission, letting other users know the speaker has released the channel. Clips of that tone have circulated on soundboards among fans of radio, emergency roleplay and German meme culture, where it is recognised instantly as a sign-off. Its appeal comes from that authenticity, turning a mundane radio function into a clear dramatic full stop.