out-of-band

adjective

a) (communications engineering) Out-of-band signaling describes signals that are sent between two parties or two devices that are sent via a path or method different from that of the primary communication between the two parties or devices.

, 2001 In this additional spectrum, in-band signaling was sent down the wires outside the frequencies used for conversation. Actually, the signals were sent across the 3,500- and 3,700-Hz frequencies. Although these worked and were not in the talk path (out of the band) they were limited in the number of tones that could be sent. — Regis J. Bates and Donald W. Gregory, Voice and Data Communications Handbook, 2001, [ page 841]

b) Out-of-band communication or out-of-band identity verification involves a program or s challenge and response to a user via a method other than the primary means of accessing the software. For example, a web application might request verification of a users identity by sending that user an IM, rather than by presenting a web form for username and password entry.

, 2007 One great way of solving the phishing problem is doing out-of-band authentication. — Simon Willison, [ Google Tech Talks: The Implications of OpenID], 2007, at approximately 22:30

Ant: inband