Dialup
Dialup is a WAN connection technique established using a modem and Active PSTN line. The modem dials a number attached to another computer at the destination end and establishes a connection capable of transferring data. The modem and telephone lines work as a data transfer medium.
Usually, a dial-up connection is used as a connectivity medium with an ISP for Internet services; the user initiates a dial-up connection, and the modem dials an Internet Service Provider (ISP) phone number designated to receive dial-up calls. The ISP gets the call and establishes the connection, which usually takes about 5 to 10 seconds and is accompanied by several beep and buzzer sounds.
History of Dialup Modem
A modem is an essential object of the dial-up network. The first modems were developed during the 1950s for military use between North American Air Defense bases. These early modems were only available for military use, and their maximum data rate was 300bps.
In 1962, AT&T introduced the first commercial modem, Bell 103. This modem’s maximum data-sending rate is also 300 bps. It provides full-duplex transmission capabilities and a frequency shift keying (FSK) feature.
Modems became a popular commercial technology in the 1990s. Most people started using modems for internet and intranet connections. Dr Brent Townshend introduced the 56K Modem in 1996, which offered a bandwidth of 56Kbps. At that time, 56 Kbps speed was the fastest internet connection for general people.
The Function of Dialup Modem
Dialup WAN connection is essential when no other WAN technology is available. For example, a remote location where only a telephone line is available can use a dial-up modem and analog telephone lines for a WAN connection. It is appropriate when irregular, low-volume data transfers are needed.
The dialup modem can transport computer binary data through the voice telephone network. The modem does this using two techniques: Modem = Modulate and Modem = Demodulate. It modulates the binary data of a computer into an analog signal at the source and demodulates the signal back to binary data at the receiving side. The physical characteristics of the analog lines limit the rate of the signal up to 56 kbps.
Dialup modems became popular due to the simplicity of analog lines, availability, and low cost. The main disadvantages of dialup network connections are the low data rates and relatively long connection time. Due to the dedicated circuit, the delay or jitter for point-to-point traffic became less, but it is not a better solution for real-time traffic like voice and video calls, online gaming, etc.
At present, only some enterprises maintain dial-up access. However, it is still a feasible solution for remote areas with limited WAN access options. Dial dial-up connections are enough for small enterprises to exchange sales figures, prices, and reports and for email service at remote locations.