Place the phone in a room entirely devoid of sound. You must ensure that noise of any sort will not enter this area.

An anechoic chamber is preferred, should one be immediately available to you (consult your local directory).

Next, direct a discerning ear towards the suspect phone, while taking care to minimize one’s own audible emanations.

If whispering is observed from the subject phone, promptly depress any button(s) labeled “End.”

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