ringdown
(redirected from Automatic ringdown circuit)ringdown
[′riŋ‚dau̇n] (communications)
In telephone switching, that method of signaling an operator in which telephone ringing current is sent over the line to operate a drop or a self-locking relay and lamp.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.