Digital Subscriber Line, DSL, Internet provides broadband service over telephone lines. DSL is significantly faster than the original dial-up configuration. Internet service providers usually offer speeds up to 1.5 megabits per second for downloading and 128 kilobits per second for uploading. Cable and satellite services are faster but more expensive.
DSL can achieve up to 3 mbps in some cases, but usually is limited to 1.5 mbps for various reasons, such as the quality of the telephone lines and other equipment. Service providers usually offer a lower speed for uploading because a large majority of customers spend almost all their time downloading, in activities such as browsing Web sites, saving files and programs to their computers, or receiving email. Uploading includes sending photos to Web sites, sending email, and posting comments in chat rooms. Providing a narrower bandwidth for uploading allows the DSL company to offer service to more customers.
Dial-up modems have a maximum speed of 56 kbps, but even in the best circumstances usually only provide 40 to 50 kbps. In rural areas with old telephone lines, speeds can be limited to around 28 kbps. Dial-up also does not allow a person to talk on the telephone when that particular line is being used for Internet access, while DSL does have this capability.
The DSL speed which the customer actually obtains at home usually is much slower than the Internet Service Provider (ISP) advertises. Phone
line quality may not support the 1.5 mbps rate, and speeds vary depending how far away the residence is from the closest telephone company hub. High traffic at certain times of day also slows down the service. In addition, phone lines have electrical interference noise from factors such as phone lines passing by electric power lines, and electrical items running in the home. Radios, microwave ovens, refrigerators, television sets, and many other items emit radio waves which disrupt telephone service to some degree. DSL providers supply phone jack filters to decrease this noise.
Cable subscribers can receive up to 7 mbps for downloading and occasionally up to 11 mbps, along with 768 kbps for uploading. Streaming audio and video media, along with gaming activity, will usually work significantly better with cable than with DSL. However, some customers dealing with old cable lines will encounter speeds similar to those of DSL, and high traffic causes problems with cable as well.
DSL is less expensive than cable, and this appears to be a middle ground which satisfies many customers. About 46 percent of broadband users in the United States subscribe to DSL, with about 39 percent to cable, according to a Pew Internet & American Life Project report from 2008. Cable is not available in all areas that DSL is, however, which likely accounts for some of the higher percentage. Other users can access the Internet through satellite or wireless service.