Just as memorable: the inevitable flop. Airtime was ill-conceived for many reasons (desktop instead of mobile, confusing use-case, the site was buggy), and the product — a video chat system — never lived up to its hype. The company quickly became a punch line. Layoffs ensued. At one point a reporter pointed out that literally no one in the world was using Airtime. Parker said the whole experience was “like eating glass.”

And yet, I continued to see Airtime nametags at tech parties and meetups. LinkedIn accounts declared new jobs at Airtime. Last March, TechCrunch reported that Airtime had recruited Daniel Klaus, who founded a media incubator called K2, to lead a complete reboot of the company. Parker would remain CEO, but Klaus would run things as President. (It’s currently unclear how large of a role Parker or Fanning have in OkHello’s day-to-day operations.)

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Now, almost a year later, Fortune has discovered, and sources have confirmed the reboot. The hyped-up startup has taken the exact opposite approach this time around. Rather than a big, flashy launch, Airtime has kept its latest project on lockdown for the last 10 months.

It’s called OkHello, and it’s been live in the App Store since last April. OkHello has been featured by the App store 46 different times in 28 countries, but never by a tech blog or news outlet. It appears to have recently launched on Android as well.

OkHello has carefully hidden any connection to Airtime. But subtle clues reveal who’s behind the app. As an intrepid Quora poster points out, Airtime and OkHello’s branding and illustrations have the same distinctive style (including a recycled script “hello”), courtesy of Airtime’s illustrator, Shayma Golden, who has been at the company for more than two years.

OkHello/Airtime did not respond to requests for comment.

More surprising than how long the app’s been kept a secret is the fact that it’s actually working.

OkHello has been in the App Store’s top 100 social media apps for the majority of the time it’s been live, according to app analytics service App Annie. It’s hit the top 10 on several occasions.

So what is it? Similar to Airtime, OkHello is a video chat service, except on mobile instead of desktop. From the app’s own description:

OkHello makes group video spontaneous and simple. It’s perfect for connecting friends, families, and all kinds of groups on video.

Users can share photos, videos and text chats, and toggle between texting, audio chatting, and video chatting. And there are stickers, too. Kids love their stickers.

After its failed launch, it’s easy to see why Airtime would want to keep its latest project under wraps for as long as possible. But it was bound to come out as OkHello grows in popularity. Thanks to WhatsApp’s $19 billion sale to Facebook (FB), all eyes are on mobile messaging. Now we know who’s behind the category’s latest up-and-comer.