Spam calls are bad enough. What about spam ads after you make a call?
That’s exactly what DoubleVerify’s Fraud Lab has uncovered: a growing and ongoing mobile ad fraud scheme that serves up annoying, intrusive ads immediately after you finish a phone call.
Here’s what the scheme looks like in action:
DV calls them “AfterCall” ads. The company says it discovers dozens of apps using the tactic each month, collectively generating hundreds of millions (!) of ad impressions.
Why This Matters:
AfterCall apps exploit Android functionality to serve ads outside the normal app experience. The apps convince users to grant permission to display content over other apps, then detect when a phone call ends and immediately serve an ad. (Innovative!)
The scheme is also designed to make the source of the ad difficult to identify. According to DV, some apps actually remove themselves from the phone’s recent apps list after serving an ad and use icons resembling everyday utilities like clocks, calendars, or notes to trick users. This, of course, makes it harder for people to figure out which app is responsible and uninstall it.
For advertisers, that means potentially paying for impressions that users never asked for — and probably don’t want.
Experts React:
DV’s Fraud Lab says AfterCall apps are particularly difficult to detect because some of the underlying Android functionality they exploit is also used by legitimate apps, including caller ID services.
Per DV cybersecurity researcher Nir Danon:
“This kind of communication is part of what makes our phones feel so fluent and responsive. However, this can also be exploited by apps with ulterior motives. Fraudsters often use it to trigger the out-of-context behavior in their apps.”
Traditional static detection methods also struggle because individual developers can implement their own variations of the scheme. DV says its AI-powered fraud detection identifies the behavior across the variations it has observed.
Our Take:
This is a good example of how mobile ad fraud doesn’t necessarily need to involve fake users or fake clicks. Sometimes the impression itself is technically delivered to a real person — just in a place where an ad has absolutely no business appearing.
And that creates a second problem beyond wasted spend: consumers don’t know which obscure app is responsible. They just know which advertiser suddenly appeared on their screen after they hung up the phone. That turns fraudulent inventory into a brand reputation problem, too.
AdTechRadar is owned by Chris Harihar, an EVP at Mod Op. DoubleVerify is a Mod Op client.
