IVR system
IVR system is the automated voice that you hear when you call some company! This automated voice helps direct the user through a series of steps that the user has to go through to complete a task. They can either use touch tones, dial tones from the keypad or even use their own voice. Basically it eliminates the need for an actual person to do the work when the computer can do it all! It can do simple tasks to very advanced ones, either way its a very useful to be using.
Freeswitch
Freeswitch is an open source communications piece of software that can be used for the creation of voice/messaging tools. It can be used as a standalone application, or embedded and ran with other programs.
List any sites, books, or sources utilized when researching information on this topic. (Remove any filler text).
This link above is showing real world applications of the freeswitch and how well it worked in real life. Freeswitch is like a phone that will use voip, and if you implement it right with say, oh i dont know asterisk, you can eventually get a free phone service going in your LAN. Now people have made it able to be used with WAn, like where they can call other people not in your network or in your config files and that link above will show that. other than that, i dont really know how else to demonstrate but to show where it can be used in real life.