A T-1 line actually consists of 24 individual channels, each of which supports 64 Kbps. Each 64 Kbps channel can be configured to carry voice or data traffic. Most telephone companies allow customers to buy some of these individual channels, known as fractional T-1 access. Cable systems were originally designed to deliver broadcast television signals to subscribers' homes. To deliver data services over a cable network, one television channel is typically allocated for downstream traffic to homes, and other another channel is used to carry upstream signals.
Most cable modems are external devices that connect to a personal computer.
Cable modems provide access speeds from 500 Kbps to 2.5 Mbps or more and they offer constant connectivity. Southwestern Bell provides both ISDN and DSL services. Southwestern Bell spokeswoman Amy Schneider said Bell's LAN ISDN is good for businesses with low to medium usage, while users can enjoy the convenience and speed of a dedicated access service at a fraction of the price. Southwestern Bell's LAN ISDN is suited for companies new to the Internet or currently using multiple individual dial-up accounts, remote company locations not on the corporate network or growing organizations looking for easy migration to higher speed access in the future, she said. Southwestern Bell has begun an aggressive DSL rollout throughout Arkansas, Kansas, Missouri, Oklahoma and Texas.