If you chose a specific model, click the model name, as shown in Figure 15-23.

Chapter 16 ✦ Accessing the Internet The only analog modem speed you can buy these days is the 56 kilobits per second Kbps. The speeds are not, however, truly 56 Kbps, because the FCC regulations prevent 56 Kbps support in the United States. Downloading speeds for a 56 Kbps modem are 53 Kbps, and uploading speeds are only 33 Kbps. Also, the actual speed depends on the phone line condi- tions and the current connection. A storm, for example, or interference from other sources, can slow connections through a phone line. Using digital modems A digital modem is a piece of hardware that transmits data in both directions, usually simulta- neously, at high speeds. You use certain types of digital modems for the connection types you’ve got. If you have a DSL, for example, you use a DSL modem, which is a modem built specifically for use with that type of line. Sometimes a digital modem is called a terminal adapter TA or router, but the process is still the same. A piece of hardware located at the end of the line — DSL, TV cable, ISDN, and such — transmits and translates the signal to and from the computer or server. When there’s a digital modem on one end of the line, there must be a digital modem on the other end of the line for the two to communicate. Integrated Services Digital Network ISDN is a telecommunications network that enables digital voice, video, and data transmission. ISDN was quite popular among small businesses until cable modems and DSL became more common and available. ISDN only offers 128 Kbps speeds for data transfer. Figure 16-7 shows a cable modem connection between a home user, the ISP in this case, the cable company, and the Internet. The cable modem in the home is connected, by coaxial cable, to the cable modem at the cable company’s building. Note that multiple lines feed from the ISP to a larger Internet provider. Note Modem Standards The ITU International Telecommunications Union defines standards for telecommunications that govern, in part, the definition of modem speeds and operations. The ITU also governs fax and digital modems. For example, V-standards define speed, wiring, and error correction in modems and other telecommunications devices. V.32 bis is an ITU standard for 14,400 bps modems. V.33 is an ITU standard for 12,000 and 14,400 bps modems used over four-wire, leased circuits. V.34 defines a 28,800 bps modem over a dial-up line, with error correction and data compression techniques included. The V.90 standard used for 56 Kbps modems is now the most common standard. Part IV ✦ Adding the Internet, E-Mail, and an Intranet Figure 16-7: ISPs feed into larger ISPs, which feed into larger ISPs, and all together, these servers form the Internet. Sharing Internet Connections Dial-up modems are not shareable over a local area network under normal conditions. With the use of a third-party application, however, you can surf the Net and send and receive e-mail at the same time others on the network use the Internet connection. Various programs exist, often called proxy servers, which enable you to turn one phone line into multiple Internet connections. Many people use cable modems or DSL modems in their home or small business for Internet connections instead of using dial-up modems. You can also use a software program or a hard- ware device, often called firewall routers, to share these modems. Basically, these applications or devices enable all computers on a LAN to connect to the Internet, surf the Web, and send and receive e-mail simultaneously, using one Internet connection. Some ISPs have policies against sharing an Internet connection. Check with your ISP for more information. When using the proxy applications, you usually have to install TCPIP to each computer on the LAN. Additionally, you install the proxy software on the host, or server, machine first; this is the computer that’s attached directly to the dial-up or cableDSL modem. Then you install the software on client or guest machines. Tip Internet Cable modem Cable company