out-of-band

out-of-band

Separate from the primary frequency or system. See signaling in/out-of-band and out-of-band data.

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1.	(communications)	out-of-band - The exchange of call control information on a dedicated channel, separate from that used by the telephone call or data transmission.
2.		out-of-band - Sometimes used to describe what communications people call "shift characters", such as the ESC that leads control sequences for many terminals, or the level shift indicators in the old 5-bit Baudot codes.
3.		out-of-band - In personal communication, using methods other than electronic mail, such as telephone or snail-mail.
4.	(software)	out-of-band - Values returned by a function that are not in its "natural" range of return values, but rather signal some kind of exception. Many C functions that normally return a non-negative integer return -1 to indicate failure. This use confuses "out-of-band" with "out-of-range". It is actually a clear example of in-band signalling since it uses the same "channel" for control and data. Compare hidden flag, green bytes, fence.