Off-hook dialing
The Wiki of Unify contains information on clients and devices, communications systems and unified communications. - Unify GmbH & Co. KG is a Trademark Licensee of Siemens AG.
Explanation
The condition that exists when a telephone or other user instrument is in use, i.e., during dialing or communicating. Note: off-hook originally referred to the condition that prevailed when telephones had a separate earpiece (i.e., receiver) which was removed from its switchhook. The weight of the receiver no longer depresses the spring loaded switchhook thereby connecting the instrument to the telephone line.