Earlier this month, I shadowed several restaurants throughout New York and talked to restaurant employees across the US to see how they’ve received Google Duplex, the AI that makes life-like calls for reservations on your behalf. Most if not all agreed that those calls sounded unmistakably human — and according to Google’s response to reporting by The New York Times, there’s a 25 percent chance that they were.

Google says that a quarter of Duplex calls start with human callers, and 15 percent start with the AI and are later intervened by a person from the Duplex call center. The company told The New York Times that it uses a variety of signals to decide whether a call should be placed by a human or a robot, “like if the company is unsure of whether the business takes reservations, or if the user of the assistant might be a spammer.”

Google Duplex works by first attempting to make reservations with restaurants that offer online booking tools through platforms like OpenTable, Resy, and Yelp. If those options are not available, then it will deploy the voice-calling AI. As this technology is still rather young and limited — the feature launched publicly late last year and expanded to iPhones just this past April — Google says it is still using human callers to help obtain data to train its AI and eventually decrease the need for human involvement.

All the while, restaurant workers are left to contend with calls they describe as creepy or confusing. In one instance while I was shadowing a waitress at a gastropub, Duplex called twice several minutes apart for a single reservation, using two different accents to confirm the booking. In other instances, though, some restaurants aren’t even picking up Google Duplex calls at all since the caller ID looks potentially like spam.

Google says it plans to roll out Duplex to other businesses like hair salons, but so far it looks like there’s still more testing to do until the service can scale. The Verge has reached out to Google for additional comment, and will update this piece if we hear back.