At the data terminal equipment/data circuit-terminating equipment (DTE/DCE) interface, a steady-state condition that indicates that the DCE is not ready to accept a call-request signal or that the DTE is not ready to accept an incoming call.

1. A method of changing a key-enciphering key so as to confirm the identities of the originator and the ultimate recipient. [After X9.8]
2. The registration of data with a trusted third party that allows the later assurance of the accuracy of its characteristics such as content, origin, time and delivery [7498-2].

In a relatively wide band of frequencies, not necessarily of uniform amplitude, a narrow band of frequencies having relatively low amplitudes.

Synonym band-stop filter.

Noise from which a narrow band of frequencies has been removed.
Note: Notched noise is usually used for testing devices or circuits.

Abbreviation for neper.

Abbreviation for numbering plan area.

NPA code relief refers to an activity that must be performed when and NPA nears exhaust of its 792 NXX capacity. Options for relief are described in Section
6. 0 of the NPA Code Relief Planning & Notification Guidelines.

The date by which the NPA is introduced and routing of normal commercial traffic begins.

Number Portability Administration Center