Etherloop uses half-duplex transmission, and as such, is less susceptible to interference caused by poor line quality, bridge taps, etc. Also, etherloop modems can train up through line filters (although it is not recommended to do this).
Etherloop has been deployed by various internet service providers in areas where the loop length is very long or line quality is poor. Some etherloop modems (those made by Elastic Networks) can be set in "Central Office" mode and you can connect them back to back over a phone line and use it as a LAN extension. An example of a situation where this would be done is to extend ethernet to a building that is too far to reach with straight ethernet.
Independent Telephone Companies Use Elastic Networks Solutions.(Etherloop technology)(Brief Article)(Statistical Data Included)
Apr 01, 2001; Editor's Note: NTCA members continue to explore and actively use advanced technologies to bring high-speed broadband access to...
Nortel has a DSL of its own. (Northern Telecom Elite 1 modem, Elastic Modem multiplexer for DSL)(Product Announcement)(Brief Article)
Mar 23, 1998; Nortel this week will announce modems that support a new digital subscriber line (DSL) technology which is set apart from other...