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Dial-up Modems
The term modem stands for modulator-demodulator which is a description of how it works. The term modem was used to describe the technology used by dial-up modems. Though High Speed Cable and DSL boxes are often called modems the name is actually a misnomer. Modems work by sending analog wave frequencies in the form of sound over a telephone wire.
Once the signal from the modem is received by the other side, a "handshake" process occurs in which the modems try to establish communication with one another. Once the "handshake" process is complete and has succeeded the modem can talk with either an ISP or another modem over the telephone network.
The maximum speed achievable over the telephone line is 33,600bps. How do 56,000 bps modems achieve faster speeds then? So called 56k is possible due to the fact that ISP's generally have all digital networks up to the point of the Central Office. From the Central Office to a user's house the signal is usually analog. The analog part of the connection from the user's house to the Central Office, while only capable of 33,600bps, is able to achieve faster speeds due to the faster digital network of the ISP which the signal piggy backs on part of the way. In reality, achieving 56,000bps is near impossible. Generally speeds in the 40,000 -49,000 range are considered good. Often due to poor quality lines, or Load Coils used to boost line quality for voice calls, speeds may not exceed 33,600bps.
It should be apparent that speeds can vary a great deal with 56k technology. Speeds can range from a low of 26,400 - 53,000bps. There are 3 different technologies offered to achieve 56k they are K56flex, X2, and V.90. A new revised V.92 standard was also recently added. These standards are mostly incompatible with each other. Often if your modem supports one standard and the remote modems of your ISP another standard you will be unable to achieve 56k speeds.
In order to acheieve the fastest speeds possible on 56k ensure the following:
- Your ISP supports the technology used by your modem to achieve 56k (i.e. k56flex, X2, V.90, V.92).
- Try not to pass the phone cord from your modem through other connections such as a fax machine. (i.e. run a phone cable directly from the modem to the phone jack)
- Use a short phone cable between your modem and phone jack preferably between 6 - 10 feet
- Ensure your modem firmware is updated to the latest revision
- Use a hardware based modem if possible. They tend to cost more but are worth the moeny due to the fact that they have built-in hardware to do the compression/decompression.