MasterClass is expanding beyond pre-recorded video lessons to offer on-demand mentorship from some of its most popular celebrity instructors. And if you’re wondering how the company has gotten some of the busiest people on the planet to field your questions, guess what? The answer is generative AI.

On Wednesday, MasterClass debuted On Call, a new web and iOS app that allows people to talk with AI versions of its instructors. As of today, On Call is limited to two personas representing the expertise of former FBI hostage negotiator Chris Voss and University of Berkeley neuroscientist Dr. Matt Walker. In the future, MasterClass says it will offer many more personas, with Gordon Ramsay, Mark Cuban, Bill Nye and LeVar Burton among some of the more notable experts sharing their voices and knowledge in this way.

“This isn’t just another generic AI chatbot pulling data from the internet,” David Rogier, the CEO of MasterClass, . “We’ve built this with our experts — training the AI on proprietary data sets (e.g. unpublished notes, private research, their lessons, emails, [and] expertise they’ve never shared before).”

Per , MasterClass signed deals with each On Call instructor to license their voice and expertise. Judging from the sample voice clips MasterClass has up on its website, the interactions aren’t as polished as the one shown in the ad the company shared on social media. In particular, the “voice” of Chris Voss sounds robotic and not natural at all. On Call is also a standalone product with a separate subscription from the company’s regular offering. To use On Call, users will need to pay $10 per month or $84 annually.