Networking: A Beginner’s Guide Fifth Edition- P21:I have run into many people over the years who have gained good even impressive working knowledge of PCs, operating systems, applications, and common problems and solutions. Many of these people are wizards with desktop computers. | 82 Networking A Beginner s Guide The maximum theoretical speed of basic analog POTS is Kbps. Many factors can decrease this speed chief among them is line quality. Telephone lines with static typically do not connect at the top speed of Kbps and they might lose their connections unexpectedly lose data being transmitted or pause for excessive periods of time as bursts of static inhibit the ability to transfer data. When you are using POTS to establish a network connection having matched modems at both ends is optimal. Matched modems from the same manufacturer more easily negotiate the highest possible data transmission rates and often can support step-down modes which automatically use a slower speed when line noise unexpectedly becomes a problem. POTS transmits analog signals not digital ones. The data sent between systems is converted from digital data to analog data using a modem. The word modem is actually an acronym based on the device s function modulator demodulator. At each end of the connection the sending system s modem modulates the digital data into an analog signal and sends the signal over the telephone line as a series of audible sounds. At the receiving end the modem demodulates the audible analog signal back into digital data for use with the computer. With much higher speed Internet connections being ubiquitous these days POTS is not often used for transmitting data except in extremely rare cases. However given its heavy past use and the remote chance that you might run into a system using a POTS connection for some type of data transmission you should be familiar with it. Integrated Services Digital Network ISDN ISDN stands for Integrated Services Digital Network. It is a high-speed digital communications network based on existing telephone services. Although it has existed for more than ten years because of extensive upgrades required at telephone company central offices COs it has not become widely available until recently. Even now it
