We all know that getting your app on to user’s phones is no easy task. We know too that having it on there is no guarantee of them using it on a regular basis. So if, as an app developer, you rely on in-app ads to make money, you’re going to struggle if your users are only coming back to the app infrequently.

This is the problem Calldorado aims to solve. The one-year old startup offers Android developers a way to monetise their apps, even if they are not being opened up and used by the person whose phone they are on. So how does that work?

The trick is in Calldorado’s SDK, which the app developer integrates into their own app. From this point on, so long as the user agrees to it, whenever they make or receive a phone call on their mobile, the SDK will enable the phone to display the caller’s ID, by looking it up on an external database. This is displayed at the top of the phone’s screen on an overlay. When the call ends, a display ad is shown in the bottom third of the screen, with Calldorado taking 30 per cent of the revenues, and the app developer 70 per cent. Users can opt out of seeing the ads at any time.

If the user has more than one app on their phone with the Calldorado SDK integrated, the first of these apps will take the revenue, though Calldorado founder and CEO Claudia Dreier-Poepperl, told me yesterday that in time, it could move to a rotation model, where the revenues are shared between all apps on the phone that have integrated the SDK.

This does sound like a great trick for the app developer, especially as the ad unit can incorporate a link to take the user back to the app, perhaps for the first time in weeks. But what about the user. If you make or take a dozen phone calls in a day, do you really want to see an ad each time?
In fact, Dreier-Poepperl told me yesterday, because Calldorado is transparent about permissions, making it easy for users to switch the service off, it sees around 70 per cent of people staying with the service.

“The ads are targeted,” she told me. “Like other networks we know things about the users like the app IDs from Google, so we can create a persona and try to show relevant information to the caller. And if we know they have just called a car workshop, then maybe they are in the market for having some work done on their car, so we can show them a relevant ad.”

There are around 2,000 apps out there with the Calldorado app installed, including many in Asian markets, with in excess of 50m users. We are getting good traction with apps all around the globe, with lots of Chinese and Indian publishers jumping on,” said Dreier-Poepperl. “Most have a lot of apps in their portfolio, so they try with one and if it works they roll it out to the others.”

So what next? “When you have found something that works and can scale, you need to focus on that, and that’s what we’re doing,” she says. “We will extend it to have more ad formats on it and we will help developers to grow their apps with more innovative models. The app business is all about reach which is getting more users and this is increasingly. So you need buy your way into it by buying installs in a smart way and then having the monetisation technology to recover the money paid for the user in a relatively short time, and then turn the app into a cash cow, which is what we believe is needed to survive and grow big. We’ve been doing it for many years with our own app portfolio, and we know it works.”