The expansion of accessible internet service provider connectivity since that time has rendered the practice more or less obsolete.
While Speed dial technology had been invented nearly a decade earlier by Bell Labs, it did not become a consumer product until deregulation.
[2] Previously, connecting non-AT&T handsets was generally prohibited and most phones were leased devices (similar to residential broadband routers).
By putting its functionally in a line-connected appliance rather than a handset, the Demon Dialer device could be configured to provide speed dialing to all extensions within a residence through touch tone control.
[3] After giving the program an area code and 3 digit prefix, the program then serially dialed every phone number in that prefix in order, recording which phone numbers were answered by a computer modem.