If you suspect your colleague across the globe is actually filing her nails or checking Facebook while on a conference call with you, you're probably right.

New data released Tuesday by InterCall, a conference call company used within 85 percent of Fortune 100 companies, reveals the professional, commercial and personal activities people are doing while on the other end of the line. In a survey of 530 office workers, which was first reported by the Harvard Business Review, 65 percent of respondents said they had done other work while on a conference call, and 63 percent said they had sent email.

"This is not multi-tasking," said Dennis Collins, a director of marketing at InterCall. "It's semi-tasking. People think they're doing multiple things, but they're not doing anything well."

Other responses were further afield from the business of work. Fifty-five percent said they had eaten or prepared food while on a call, and 25 percent said they had played video games. A full 47 percent said they had used the bathroom while on the line. "Hopefully those were not video calls," Collins said.

Some people reported that they didn't even pretend to multitask. Nearly 40 percent said they had dropped off a call without saying so, pretending they'd stayed, while 27 percent admitted to falling asleep. Thirteen percent said they had been "outed" for not being in the location they'd claimed to be, and a handful — five percent — said they'd had a friend take a conference call in their place.

"That one threw me for a loop," Collins said. "But if you have an invitation for a webinar call or an online monthly staff call, [the friend] would just click the link. It's a ghosted presence," he called it.

In the survey, people also admitted to some pretty strange places where they'd taken such calls: a closet at a friend's house during a party, a truck stop bathroom, a fitting room while trying on clothes.

Maybe next time a conference call gets boring, entertain yourself by wondering where your colleague is actually taking the call — or what else he might be doing simultaneously. That is, if you're not shopping online or making a trip to the restroom yourself.

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