Internet Service Providers (ISPs)

Internet service providers (ISPs) enable businesses to connect to the Internet. Large-scale ISPs offer private line hookups such as ATM, T-1, T-3, and fractional T-1. Asynchronous transfer mode (ATM) is a high-speed, high-bandwidth, packet switching and transmission system which Internet service providers (ISPs) use to ntegrate voice, video, and data communications. ATM or cell relay uses fixed-sized packets called cells. T-1 lines have 24 voice or data channels and can reach transmission speeds of 1.54 Mbps. T-1 lines are used by small and medium-sized companies with heavy network traffic. T-3 lines provide up to 28 channels and can achieve transmission rates of 44.74 Mbps. These leased line connections are relatively expensive to maintain and suitable for only the largest networks. Some Internet service providers (ISP) offer fractional T-1 lines as an alternative to a full T-1 or T-3 connection. Fractional T-1 is a point-to-point arrangement in which a multiplexer channelizes a carrier’s signals.