I have read that a significant drawback of telephone lines, one that makes difficult fast digital data transmission is the fact that they are inductively loaded. Now in telephone ADSL lines, are these inductors removed?

  • \$\begingroup\$ Many years ago, before the internet and ISDN, inductor line loading to achieve 600 ohm resistive impedance died a death. \$\endgroup\$
    – Andy aka
    Nov 16 '18 at 18:26
  • \$\begingroup\$ @Andyaka, in some places it made a short comeback when people started using DSL modems on dialed lines, gently nudging customers to "proper" DSL offerings. \$\endgroup\$ Nov 16 '18 at 19:58

My understanding is that (1) historically, "load[ing] coils" were added to telephone lines at intervals to compensate for line capacitance when extending them very long distances; (2) any such coils did and do have to be removed for DSL service; but (3) in general, very long lines (such as might need load coils) are not suitable for DSL service anyway. (This might be less true now than it was in the early days of DSL.)


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