Abstract: A two-path equalizer system interposable in a telephone line carrying supervisory signals whose frequencies lie below a 3 KHz limit and data signals whose frequencies primarily lie above this limit. The system normally operates in a first path mode with respect to incoming supervisory signals, the gain in the first path being preset to a degree depending on line losses, whereby the levels of supervisory signals emerging from the output of the system are at their nominal telephone line levels. An automatic path selector is provided which is responsive only to data signal frequencies and acts to switch-over the system and render it operative in a second path mode in which incoming data signals are subjected to automatic gain control and appear at the output at their maximum line level despite variations in input level.