In a signal, any instant at which a significant condition of a signal begins or ends.
Note: Examples of significant instants include the instant at which a signal crosses the baseline or reaches 10% or 90% of its maximum value.

The time interval between two consecutive significant instants.

In digital telephony, a code composed of a reserved binary number that is sent instead of an actual sound sample value from the CODEC when the incoming voice volume is below a certain level (i.e., when there is no sound). Depending on the transmission system used, the silence code is used for two purposes: (a) to allow other (lower priority)… (Read More →)

Any portion of a ringing cycle during which the ringing signal is not being applied. [T1.401-1998]

Synonym skip zone.

Silicon dioxide (SiO2).
Note 1: Silica may occur in crystalline or amorphous form, and occurs naturally in impure forms such as quartz and sand.
Note 2: Silica is the basic material of which the most common communication-grade optical fibers are presently made. [After FAA]

See silica.

A silicon-based PN- or PIN-junction photodiode.
Note 1: Such photodiodes are useful for direct detection of optical wavelengths shorter than approximately 1 m.
Note 2: Because of their greater bandgap, silicon-based photodiodes are quieter than germanium-based photodiodes, but germanium photodiodes must be used for wavelengths longer than approximately 1 m. [FAA]

Session Initiation Protocol for Instant Messaging and Presence Leveraging Extensions

Authentication by means of simple password arrangements. [After X.509]