Do you remember answering machines? They were a precursor to voice mail systems of today. In 1986, Scott Jones and Greg Carr started Boston Technologies, and began working on a system where you could dial a number and find out stock information. One good idea led to another and the pair thought they could provide people with built in voice mail.
Until 1988, all phone companies besides AT&T were legally banned from providing voice mail. When the ruling was reversed, the pair approached several telecom companies and got financial backing. Within 3 months, their ideas were realized. Voice mail is slowing in popularity with some age groups due to text messaging, but is still a staple of the telecommunications industry. I don't think voice mail will be replaced for a while.