Dial-up Internet access
Dial-up Internet access is a form of Internet access that uses the facilities of the public switched telephone network (PSTN) to establish a connection to an Internet service provider (ISP) by dialing a telephone number on a conventional telephone line. Dial-up connections use modems to decode audio signals into data to send to a router or computer, and to encode signals from the latter two devices to send to another modem at the ISP. In 1979, Tom Truscott and Jim Ellis, graduates of Duke University, created an early predecessor to dial-up Internet access called the Usenet. The Usenet was a UNIX based system that used a dial-up connection to transfer data through telephone modems. Dial-up Internet has been around since the 1980s via public providers such as NSFNET-linked universities. The BBC established Internet access via Brunel University in the United Kingdom in 1989. Dial-up was first offered commercially in 1992 by Pipex in the United Kingdom and Sprint in the United States. After the introduction of commercial broadband in the late 1990s, dial-up Internet access became less popular in the mid-2000s. It is still used where other forms are not available or where the cost is too high, as in some rural or remote areas. For example, the U.S. states of Maine and Georgia have a much higher percentage of people using dial-up compared with the rest of the United States. Because there was no technology to allow different carrier signals on a telephone line at the time, dial-up internet access relied on using audio communication. A modem would take the digital data from a computer, modulate it into an audio signal and send it to a receiving modem. This receiving modem would demodulate the signal from analogue noise, back into digital data for the computer to process. The simplicity of this arrangement meant that people would be unable to use their phone line for verbal communication until the internet call was finished. The Internet speed using this technology can drop to 21.6 kbit/s or less.
