The limit on dialup modems is imposed by the end-to-end quality of the network. Even though your subscriber loop may support DSL speeds, the network is limited to approximately 3 kHz of bandwidth, enough to support voice calls. In normal telephone service, your subscriber loop is attached to a SLIC (subscriber loop interface card) at the central office. The SLIC translates between the analog signal on the subscriber loop and the 64 kbps digital signal used for voice calls inside the telephone system. The only analog part of the modern telephone system is the subscriber loop. To provide DSL service, the subscriber loop is removed from the SLIC and connected to a different card that has both a DSL modem and the circuits of a SLIC. The low (audio) frequencies go to the SLIC and the higher frequencies go to the DSL modem.
Hmm. Reading the Wiki indicates I was only familiar with the network engineering definition, but it’s good to know the more common application of “broadband” wasn’t thought up by some marketdrone.
Yep. Sometimes technical terms actually do retain their proper meaning. It amazes me when that happens, too.