Place your Wistiki near your smarpthone.
If you keep your finger pressing on your Wistiki, the smartphone should ring.
The more the volume of your smartphone is turned up, the louder it will ring.
Your smartphone doesn't ring when you press the Wistiki's button ? (Make sure your smartphone's volume isn't at 0)
Case 1 : if the "Ring" button is shaded in orange (when pressing the "ring" button, the Wistiki rings), the app needs to be closed (go to the app center, then slide the app to the side) then opened again. This will fix the problem.
The app update fixes this problem.
Case 2: if the "ring" button is grey (when pressing the button, the Wistiki doesn't ring), the solution lies here.