The Sound of dial-up Internet
The dial-up sound was also called a "handshake" between the user's modem and their ISP's modem. The sound was unusually loud because the modem speaker was turned on by default to give the user feedback that something was happening during the "handshake" while the modems were "talking" with each other.
In early 1993 the fastest available modem was only capable of transferring data at a maximum speed of 14.4 kilobits per second (kbps), equivalent to 864kb per minute, or 51.84Mb per hour. However, the launch of the 28.8k modem in 1994 doubled this theoretical maximum. 33.6k modems followed in 1996, and eventually 56k modems arrived in 1998.
Due to the technology used to deliver normal phone service, the fastest modem rate available is 56 kilobits (one thousand bits) per second and in some areas (mostly rural) it is still available.
Nonetheless, the dial-up sound was the sound that most Internet users would hear until 2007 — when over 50% of the Internet users finally converted to broadband.