line conditioning
The adjustment of electrical characteristics of, e.g., twisted pair telephone lines by insertion of components such as resistors, capacitors, transformers or (commonly) inductors. Lines intended for analogue voice signals usually have inductors inserted every few miles; such a line is said to be "loaded".
The special purpose lines which have neither inductors nor the DC voltage which powers ordinary telephones are said to be "dry," and are much better for data transmission.