I mean that's pretty simple using 11labs and the schedulign template VAPI does - and if you link cal.com or google calender, it's even simpler. As to making it 100% sound like a human, that will require a high quality voice from someone like 11labs - as to making them THINK they are talking to a human, depending on your jurisdiction - this can be illegal. Even in the USA, you have to disclose outbound calls that are AI generated, and as to INBOUND calls, about 5 states have requriements to state it's AI as well.