On-Hook and Off-Hook Signals - the terms on-hook and OFF-HOOK were derived from the old telephones that use a hook to hold the handset. When the handset was removed to make or answer a call, it was OFF-HOOK. Otherwise, it was on-hook. In modern networks, a station is on-hook if the conductor loop between the user station and the end office is open, with no current (voice or data traffic) flowing. The OFF-HOOK has a dc shunt across the line, causing current to flow.