wink

In telecommunications, a wink is a signal in the form of a brief interruption in an otherwise continuous signal. Winks can be used to indicate certain conditions, or to cause specific actions to be performed by a telephone switching system.

Wink pulsing is a means of alerting an operator or user that a certain condition exists. It consists of a series of brief interruptions in an otherwise continuous signal. For example, a multi-line telephone has several buttons, one for each line, and each with a backlight. When one of the buttons is lit to indicate that there is a call on that line, the illumination is interrupted at regular intervals (usually about 1/2 second) to get the user's attention.

A wink release is the tone sent to a phone from the central office indicating that the other end of a connection has hung up. Usually, the phone receiving the wink release will then hang up, too.