Detecting deception over the telephone can be a challenge. Without visual cues, catching lies is more difficult than when you're face-to-face, but not impossible. These techniques can enhance your skills:
Be a Skeptic
Skepticism suggests to speakers that their statements lack credibility. When listeners express a degree of skepticism, liars try harder to convince them that what they said is the truth.
(Truthful people merely convey facts—because the truth is the truth.) When talking on the phone, listen closely and monitor speakers to determine if they are conveying facts or trying to convince you of the facts.
Use the Spotlight Effect
Liars believe that others can more easily detect their attempts to lie than is really the case. This phenomenon is known as the Spotlight Effect. Listeners can take advantage of this illusion of transparency and vulnerability in the liar's mind by subtly inferring that his or her attempts to deceive are readily visible. Judiciously expressing skepticism will help achieve this end.
Listen for Throat Clearing
Liars sometimes clear their throats, in a fight-or-flight response to the stress of maintaining a lie—the moisture usually present in the throat has been rerouted to the skin.
Avoid the Land of Is
Yes or No questions deserve Yes or No answers. When liars cannot, or do not want to answer Yes or No, they typically go to the Land of Is. This concept derives from President Clinton’s infamous statement, “It depends upon what the meaning of the word is is," while being questioned about the Monica Lewinsky scandal. The Land of Is occupies a space between truth and deception: Most liars want to maintain the illusion of truthfulness, so they go to great lengths contorting the English language in support of that vision, tangling up their listeners. You can thwart these efforts by asking Yes or No questions. If the speaker does not provide a Yes or No answer, repeat the question. If you still don't get a Yes or No, there's a higher probability of attempted deception.
“Well…” Is Not Good
When you ask someone a Yes or No question and they begin their answer with "Well," there is a high probability of deception. It indicates that the person is about to give you an answer that they know you are not expecting. Consider the following exchange between a telephone marketer and a potential customer:
Marketer: The product has a lifetime guarantee. No matter what happens, just send it back to us and we will replace it.
Customer: No matter what happens? (A Yes or No question—and the introduction of mild skepticism)
Marketer: Well, the guarantee only covers material and manufacturing defects. (By beginning the response with “Well,” the salesperson is going to try to give the customer any answer except Yes.)
Customer: So when you say “no matter what happens,” you really mean only material and manufacturing defects? (Another Yes or No question)
Marketer: Yes. (The truth revealed)
(Do not tell liars about this technique because they will deliberately avoid the use of the word “Well.”)
No one verbal cue indicates certain deception. However, a cluster of verbal indicators significantly increases the probability of deception. Additional techniques to detect deception on the telephone can be found here. Other verbal indicators to deception are outlined in the book, Psychological Narrative Analysis: A Professional Method to Detect Deception in Oral and Written Communications and the booklet, Catch a Liar.