Unattended calling is performed by a computerized system known by various names such as voice messaging systems, auto dialers, message delivery systems, ADADs (Automatic Dialing and Announcing Devices), telecomputers, etc. They all basically do the same thing. They hold a recorded message and then deliver that message to the list of numbers you've asked it to call. Voice messaging systems first tell the called party what you have to offer, then they record pertinent information like the name, address, phone number and best time to call. The purpose of these machines is to advertise, generate leads, make sales, notify, remind and alert. They are very effective at what they do.