Most people are looking to digital technologies like ADSL , cable modems , and ISDN . Each of these systems offers higher speed and lower latency than 56K, but price and availability can prove to be major obstacles. In some geographic regions, analog phone lines will be the only available access technology for years to come. For all the failings of analog phone lines, they're plentiful and cheap.
Electronics stores use multiplexers to show the same movie on a wall of televisions.
An inverse multiplexer takes multiple signals and bonds them into a single, usually stronger signal. Inverse multiplexing modems can bond multiple analog phone lines to double, triple, or quadruple the speed of a regular modem. The process is also referred to as multilink, channel aggregation, channel bonding, load balancing, and many other terms, but I'll refer to it here as bonding. The idea behind bonding isn't new. It was later osboleted by RFC 1990 .