Etiquette expert: The No. 1 mistake to avoid during phone interviews

For many millennials, talking on the phone is a lost art. Texting and email take precedence over actual conversations. In fact, one survey found that 74 percent of millennial respondents in the U.S. would rather send a text than talk.

But just because you may prefer to make plans with friends using emojis doesn't mean you don't need to know how to answer a call at work or ace a phone interview for a job.

The biggest misstep people make on the phone? Getting too familiar too quickly.

That's according to Kimberly Pope, founder of The Pope Institute for Polish, Poise and Etiquette. In professional situations, such as a job interview, dropping formalities and seeming too laid back can steer things off course and make you appear unfocused, she says.

"You still want to stay present in the fact that this is a business conversation," Pope tells CNBC Make It.

Follow the other person's lead. If John Smith calls you for a job interview, you don't want to respond, "Oh, hey, John." While you don't want to be overly formal or terse, jumping straight into a casual way of speaking can be considered disrespectful and could set you off on the wrong foot, Pope says.

When things become too lax, it's also easy to veer off-topic. Be careful not to waste the other person's time. "In job interviews, you want to think about the fact that this person probably doesn't have a lot of time to devote to a long-winded conversation," Pope says.

And, while a little banter can help build a rapport, focus on getting your points across succinctly.

No matter what, the key to keeping things professional on the phone is remembering what Pope deems the three principles of etiquette: consideration, respect and honesty. Be considerate of the other person's time, fully engaged in the conversation and sincere in your answers. The little things can make a big difference.

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