Recent advances in communications signal processing and VLSI technology are fostering tremendous interest in transmitting high-speed digital data over ordinary telephone lines at bit rates substantially above the ISDN Basic Access rate (144 Kbit/s). Two new technologies, high-bit-rate digital subscriber lines and asymmetric digital subscriber lines promise transmission over most of the embedded loop plant at 1.544 Mbit/s and beyond. Stimulated by these research promises and rapid advances on video coding techniques and the standards activity, information networks around the globe are now exploring possible business opportunities of offering quality video services (such as distant learning, telemedicine, and telecommuting etc.) through this high-speed digital transport capability in the copper loop plant. Visual communications for residential customers have become more feasible than ever both technically and economically.
T. Russell Hsing,
"Video on phone lines: technology and applications", Proc. SPIE 2668, Digital Video Compression: Algorithms and Technologies 1996, (22 March 1996); doi: 10.1117/12.235403; https://doi.org/10.1117/12.235403