- The condition where a telephone is in not use. This state occurs, for instance, when the handset is resting on its cradle, which keeps the hookswitch depressed. Also, when another device, such as a fax, is not in use. This contrasts with off-hook, where the telephone or other device is in use. Also spelled on-hook. Also called on-hook state, or on-hook condition.
Not what you were looking for?