Headsets (including Bluetooth ones) were already a thing back then, so they'd have to go back another couple of decades, I guess. Using the speakerphone mode in public would attract some looks though.
The AirPods of today are pretty much invisible which is why it’s genuinely impossible to tell even with a close look who they’re talking to, especially when they stare at ME because I’m staring at them trying to figure out if they’re talking to me!