If you run a call center, serving clients in a timely way is often very complex, as it requires having enough people available to handle traffic spikes. The number of callers that disconnect because they have been waiting too long in a queue is then an important driver of the quality of your work, and these frustrated callers are the focus of much attention and scheduling/planning efforts in all call centers. This is because in a traditional setting doing inbound calling you basically had no other way of servicing the client but waiting for the person to call in.
With an Asterisk-based PBX and using digital lines, this scenario changes a bit, as:
* Your average caller has an associated caller-id that often matches a physical phone in their proximity
* Telephone traffic is very cheap compared to the cost of agent time for call handling
* You have ample means of programming the PBX to suit your exact needs
So it is now a conceivable scenario to improve the services you are offering by adding an automated call-back option, so that you search the logs of lost calls and you actively schedule recalls on them in order to get back to people who hung up in frustration.
See
http://blog.wombatdialer.com/post/41774590472/autorecall