Yeah, it's a feature dubbed "queued callback". Saves your place, it's a pretty common request. Customers like Delta, Intuit, Pacific Life, Citibank, Dyson, all use the platform I build (Amazon Connect) and do stuff like that.
Problem is, no one answers a call from an unknown number these days. Some phones are getting smart enough to recognize the number and show that it's a business, though that's more anecdotal evidence from my personal device (Pixel Fold with Google Fi carrier).
That's a good point, a lot of people are still on old Avaya or Cisco systems and it was expensive to do that. A lot of cloud providers now don't charge anything for it.