Your first choice is the set of auditory cues on the phone which consists of nine clicks.
If they did not respond to those cues, the alternative set of cues is calling their name nine times in the same tempo: three words, pause, three words, pause, three words.
While the first set of cues is heard, walk about 1 yard (1 m).
Judge the speed of your changes in position by watching their eyes.
If you lose them, step back to try to regain their attention.
Press "Play" if using the phone or start calling their name.
(Insert sound)
Ending the Activity
Try for 20 seconds, or if they have stopped following, continue.