S20 is used by many different language speakers those having different English accents. S20 does not accept all command if they are pronounced slightly differently ie I have "Estonian accent " and in most cases S20 does "get me" but there is three command do fail regardless of my efforts: "muisic/stereo", "redial" and "configuration". Success rate is 1 out of 30 so its not really useful. The same time my friend can not activate a single command because Sena fails to recognize "Hello Sena" command.
More "loose" pronunciation/accent for voice commands