It's possible, but I doubt it. The person on the other end was using a Nexus 6. I don't know first-hand how its microphone is, but I know my (high-end Android)

It's possible, but I doubt it. The person on the other end was using a Nexus 6. I don't know first-hand how its microphone is, but I know my (high-end Android) phone can record voice memos with much higher sound quality than I typically hear from a phone call.