Which public WAN access technology utilizes copper telephone lines to provide access to subscribers that are multiplexed into a single T3 link connection?

The correct answer is DSL, which stands for Digital Subscriber Line. This technology takes advantage of existing copper telephone lines to deliver high-speed internet access to subscribers. DSL works by multiplexing multiple signals into a single line, allowing multiple users to share the bandwidth of a single T3 link.

This technology is particularly effective because it can provide higher speeds compared to traditional dial-up connections while allowing simultaneous voice calls on the same line. In contrast to options like cable modem technology, which uses coaxial cable and is not dependent on telephone lines, or fiber optics that use light for signal transmission, DSL maintains its reliance on pre-existing infrastructure, making it widely accessible in many areas where other high-speed options may not be available. Finally, unlike a leased line which typically provides a dedicated connection for a single user and does not utilize multiplexing in the same manner as DSL, the shared nature of DSL connections over T3 links demonstrates its unique capabilities in providing WAN access.