On what principle do Callbackhunter or Callbackkiller services work?

Question

Telephony

Is it a virtual PBX that simply connects two callers, or is everything more complicated here?

Answer 1

It just connects. There are several conditions, such as reaction time, call duration, availability, etc. on which statistics can be collected.

Answer 2

Widget on site. Pressed "Call me", entered the number. The PBX dials the operator first, then the number that was entered on the site and that's it. Freepbx, after a little shamanism, can also do this.
All their magic is in the widget (layout, text, design, display time, ease of integration) and in queues (better distributed over the operator, calculate the load, connect correctly, quickly) and tydy.