Not quite useless after all, hundreds of mostly empty phone booths in Manhattan have been rigged with transmitting “beacons” by an advertising company, BuzzFeed reports. The city’s Department of Information Technology and Telecommunications apparently allowed Titan, which sells ad space outside and on public transit, to install Bluetooth devices that send signals to smartphone apps for pinpointing a user, often for delivering location-specific messages or deals. The public was not notified, which is totally not creepy at all.

The city says Titan was given permission because it’s not collecting “personally identifiable information,” but simply using the devices for “maintenance,” whatever that means. But Gimbal, the company that makes the beacons, explains the devices in more detail:

Gimbal’s privacy policy says Gimbal-powered apps may collect your current location, the time of day you passed the beacon, and details about your device. These apps may also, under certain circumstances, collect data about the websites you visit, the apps on your phone, and the “frequency and duration of app usage.” The policy says that app-usage and website-visit data are not sent to Gimbal’s servers.

Third-party apps, at least, require users to opt in before beacons will soak up your data and perhaps beam you a coupon. But that part comes later, probably: “We are testing a number of use cases, one of which is inventory management,” a Titan spokesperson told the Daily News. “We wanted to see if beacons worked in the first place.” Comforting.

Privacy advocates are at least a little bit concerned by the vague, pay-no-attention-to-the-beacons explanations. “To the extent that the city is involved in this, the lack of transparency about this data-mining operation is … of even greater, concern,” said Donna Lieberman, executive director of the New York Civil Liberties Union. “This is an agreement that has to be suspended pending an open process about what’s going on.” On the other hand, resistance may very well be futile at this point.