The Burner mobile app generates disposable phone numbers for calls, texts and voicemail. Jeniece Pettitt | CNBC

A "burner" phone may seem more "Breaking Bad" than "Shark Tank." But an app that mimics throw-away mobile phones has found a home in the boardroom. When Greg Cohn co-founded Burner — an app that allows you to buy extra phone numbers for your regular mobile phone and "burn" them when you're done with them — he foresaw users downloading it to buy something on Craigslist, hand out to salespeople as a "spamline" or give out on Tinder. "We thought that it would be heavily about dating, privacy conscious folks, young women dating online," said Cohn, formerly of Yahoo.

But it turns out it has been a hit in what Cohn calls "the daylight cases": The business community. It has been helping entrepreneurs take customer service calls off their personal cellphones, helping bands get feedback on songs, and even collecting RSVPs at conferences.

"I was looking at different options for a work number because my co-founder and I are really mobile," said Tara Tiger Brown, co-founder of start-up KitHub, which provides educational kits for science, technology, engineering, arts and mathematics (STEAM) curriculum. "Some of the other options out there were hard to use or weren't convenient. I tried Google Voice but it was on my computer and it was always an interruption."

Burner has recently upped its bets on business, offering integration with tools like Slack, Google Docs, Dropbox and SoundCloud. For small business owners, that means customers could text a service hotline and their queries could feed into a Slack chat or spreadsheet. Important voicemails from investors could be backed up to SoundCloud.