At a developer conference in May, Google CEO Sundar Pichai demonstrated how a cutting-edge, computer-generated voice assistant called Duplex could call up a restaurant or hair salon and make an appointment without the person on the other end ever realizing they were talking with a robot. The technology was as controversial as it was impressive, drawing sharp criticism from people concerned about its ethical implications.

What Mr. Pichai didn’t mention is that the technology could be more than just a nifty trick to help users save a bit of time on reservations. Some big companies are in the very early stages of testing Google’s technology for use in other applications, such as call centers, where it might be able to replace some of the work currently done by humans, according to a person familiar with the plans.