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| The Dial-Up Modem: Traditional phone service connects you home or small business to a telephone company office over copper wires. Phone service lets you exchange voice information with other phone users through an analog signal (volume and pitch). A modem demodulates the analog signal and turns its values into a string of 0 and 1 values or digital information. This type of modem typically comes with many home computers. The fastest modems can transmit at 56,000 bits per second, although the fastest connections are generally below that connection speed. Bits: How the speed of information flow is measured. Most commonly used to show how fast a modem is, such as a 56K modem, with K representing thousands of bits. At higher speeds, such as a T-1 line, data is transferred at millions of bits per second. A bit is not to be confused with a byte, which represents eight bits. ISP: Internet service providers provide the service that allows you to connect your modem to the Internet. Some popular providers are America Online, Erols, DCANet, AT&T. T-1 Line: A T-1 line is a cable that carries data at super-fast speeds. It is more secure than a dial-up line and a cable modem because it transmits digitally and does not share the cable with other customers. It is either a dedicated Internet or office-to-office connection and is usually the most expensive. Speeds range from 1 to 3 megabits per second. Frame Relay: This is essentially a T-1 line that is shared by a number of companies. Speeds of about 1.5M can be expected. DSL: Digital subscriber lines uses regular telephone copper wires and transmits data at speeds ranging from 640K upstream and 6.1M downstream. The two most popular types of DSL are ADSL (asymmetrical DSL, faster at downloading than uploading information from the Internet); and SDSL (allows users to choose whether they want a faster download speed or a faster upload speed). This service requires a special modem and provider installation. DSL Lite: (also known as splitterless ADSL, and Universal ADSL) is essentially a slower ADSL that doesn't require splitting of the line at the user end but manages to split it for the user remotely at the telephone company. This saves the cost of what the phone companies call "the truck roll." G.Lite, officially ITU-T standard G-992.2, provides a data rate from 1.544 Mbps to 6 Mpbs downstream and from 128 Kbps to 384 Kbps upstream. G.Lite is expected to become the most widely installed form of DSL. Cable Modem: This is a system that utilizes a cable TV cable for both TV and computer transmissions. Since it is a shared line, if all of your neighbors were using it, you speed would suffer. Also, besides needing a special modem, the upload speeds are much slower that the download speeds. Cable modems can only receive and send information to the central cable office. With connections that are half as fast as a T-1 line, it is one of the most affordable alternatives in the high-speed services offerings. This service requires a special modem. |
Non-DSL Type
Speed
Time to download 33 megabyte file
Target Customers
Availability
Dial-Up Modem
Up to 56K
10 minutes
Residential/SOHO*
Now
Cable Modem
Up to 512K to 1.5M
1 minute to 23 seconds
Residential now, businesses planned
Now
Frame Relay
Up to 1.5M and is a shared line
23 seconds
Business
Now
T-1 Line
Up to 1.5M to 3M
23 seconds to 11 seconds
Business needing reliable access and security
Now
| DSL Type | Description | Data Rate Downstream; Upstream |
Distance Limit | Application |
|---|---|---|---|---|
| DSL Lite | "Splitterless" DSL | From 1.544 Mbps to 6 Mbps downstream, depending on the subscribed service | 18,000 feet on 24 gauge wire | The standard ADSL; sacrifices speed for not having to install a splitter at the user's home or business |
| HDSL | High bit-rate Digital Subscriber Line | 1.544 Mbps duplex on two
twisted-pair lines; 2.048 Mbps duplex on three twisted-pair lines |
12,000 feet on 24 gauge wire | T1/E1 service between
server and phone company or within a company; WAN, LAN, server access |
| SDSL | Symmetric DSL | 1.544 Mbps duplex (U.S. and Canada); 2.048 Mbps (Europe) on a single duplex line downstream and upstream | 12,000 feet on 24 gauge wire | Same as for HDSL but requiring only one line of twisted-pair |
| ADSL | Asymmetric Digital Subscriber Line | 1.544 to 6.1 Mbps
downstream; 16 to 640 Kbps upstream |
1.544 Mbps at 18,000 feet; 2.048 Mbps at 16,000 feet; 6.312 Mpbs at 12,000 feet; 8.448 Mbps at 9,000 feet |
Used for Internet and Web access, motion video, video on demand, remote LAN access |
| RADSL | Rate-Adaptive DSL from Westell | Adapted to the line, 640 Kbps to 2.2 Mbps downstream; 272 Kbps to 1.088 Mbps upstream | Not provided | Similar to ADSL |