Why do people keep coming to this couple's home looking for lost phones?

It started the first month that Christina Lee and Michael Saba started living together. An angry family came knocking at their door demanding the return of a stolen phone. Two months later, a group of friends came with the same request. One month, it happened four times. The visitors, who show up in the morning, afternoon, and in the middle of the night, sometimes accompanied by police officers, always say the same thing: their phone-tracking apps are telling them that their smartphones are in this house in a suburb of Atlanta.

But the phones aren’t there, Lee and Saba always protest, mystified at being fingered by these apps more than a dozen times since February 2015. “I’m sorry you came all this way. This happens a lot,” they’d explain. Most of the people believe them, but about a quarter of them remain suspicious, convinced that the technology is reliable and that Lee and Saba are lying.

“My biggest fear is that someone dangerous or violent is going to visit our house because of this,” said Saba by email. (Like this guy.) “If or when that happens, I doubt our polite explanations are gonna go very far.”

People, after all, can get pretty desperate when their tech appendages go missing. And sometimes, it’s not just a phone that’s missing, but a person. In June, the police came looking for a teenage girl whose parents reported her missing. The police made Lee and Saba sit outside for more than an hour while the police decided whether they should get a warrant to search the house for the girl’s phone, and presumably, the girl. When Saba asked if he could go back inside to use the bathroom, the police wouldn’t let him.

“Your house is a crime scene and you two are persons of interest,” the officer said, according to Saba.

The couple, who are in their 20s, she a journalist and he an engineer, worry the police will kick down their door one day, a scenario that has happened before based on faulty Find-My-iPhone tracking.

“It really drives home how unsafe and fallible some of this technological evidence is,” said Saba by phone.

The missing phones don’t seem to have anything in common. Some are iPhones. Some are Androids. They’re on different carriers: AT&T, Verizon, T-Mobile, Sprint, Boost Mobile. Saba and Lee don’t know who can fix it because there’s no obvious guilty party. They filed a complaint with the local police department but that hasn’t helped. They’ve already had two visits in 2016.

I consulted experts and phone companies to try to figure out what’s happening. They were stumped. Most experts said they needed more data to solve the mystery but were willing to speculate.

Update: We may have solved the mystery.

Ken Westin, a security analyst who used to run a device-tracking app company, says geolocation tech like this usually looks first to the phone’s GPS information (which relies on satellites), then to the cell towers to which it was recently connected, then WiFi fingerprints based on maps of WiFi networks created by companies like Skyhook, and then to the IP address, which tends to be the least accurate. He thought it sounded like a flaw in cell tower triangulation.

Something like that happened before to a man in Las Vegas. Sprint customers kept coming to his home looking for their phones. After the issue got media attention in 2013, Sprint told the Verge that the man’s home “happen[ed] to be in the center of a geometric circle denoting the coverage area of one sector of a Sprint cell site,” and that it was the default location that showed up when a more precise location wasn’t available. Sprint apologized for the inconvenience. The difference with Lee and Saba is that the phones aren’t affiliated with one carrier.

There are three cell towers near Saba and Lee’s home; the closest one is a T-Mobile tower. Both Saba and I reached out to T-Mobile to see if they could help, but the company never responded. I also reached out to Android-maker Google and iPhone-making Apple to see if they could help. No luck. I called the Federal Communications Commission, the agency in charge of regulating wireless devices; they said this type of problem didn’t fall under their jurisdiction. It seems that shrugs are as contagious as yawns.

An oddity in Atlanta’s tech infrastructure is regularly disturbing two people’s lives. A screw-up in the unseen signals flying through the air means that police and strangers are knocking on their door on a regular basis and there’s nothing obvious they can do to stop it. It’s enough to make you want to become an electrosensitive and move to the tech boonies.

“We rely on these tools and this data but we do so blindly,” said Westin. “Technology is not perfect. Law enforcement can rely on it and be wrong.”

Westin cites examples of an innocent person being charged for downloading child porn because a neighbor used his WiFi and police raiding the wrong home based on an IP address. “One piece of info is not enough to convict,” he said. “This is why you need multiple pieces of electronic evidence.”

Don Lekei of Help-My-Tech thought the problem might be that the phones were being located based on WiFi or IP address mapping. If the apps are using a WiFi map, Lekei said by email that the couple’s router could be causing the problem; if misconfigured, it could be broadcasting that it’s a different location than it actually is. Michael Saba said that at one point he reset their router, and changed the frequency at which it broadcasts; it didn’t solve the problem.

Jonathan Zdziarski, an iPhone forensics expert, first joked that their neighbors might be running a stolen device racket. Then he said he thought WiFi mapping could be to blame. He said via Twitter that it’s possible the find-my-phone apps all rely on the same WiFi mapping data—maybe all licensed from the same company— and that the company “could have had bad data in the database, either someone using the same MAC address at a different location or just bad GPS data.” Saba says that after this started happening that he registered the correct address for their WiFi network with Skyhook, but it didn’t solve the problem.

“There are probably a lot of things that could go wrong here but I’d have to have the phones to actually figure it out,” Zdziarski said via Twitter. But the phones, of course, are missing.

The most frustrating thing for Saba and Lee is that there’s no definite answer for why it’s happening, no government agency willing to take ownership over the issue, and so no way to get it to stop. Since Lee’s parents own the house, “moving isn’t an option,” said Saba.

Upon the recommendation of people with whom I spoke, Saba and Lee plan to file a complaint with the FCC and with their senator.

“Public pressure is how stuff like this changes,” said Saba. “It sucks that it happens to us, but I hope our experience will lead to it not happening to anyone else.”