Back-to-Back User Agreements

Business to Consumer

Abbreviation for bipolar with three-zero substitution. A T-carrier line code in which bipolar violations are deliberately inserted if user data contain a string of 3 or more consecutive zeros.
Note 1: B3ZS is used to ensure a sufficient number of transitions to maintain system synchronization when the user data stream contains an insufficient number of "ones" to do so.
Note… (Read More →)

Abbreviation for bipolar with six-zero substitution. A T-carrier line code in which bipolar violations are deliberately inserted if user data contain a string of 6 or more consecutive zeros. A code in which eight consecutive zeros are replaced with the sequence 000+-0-+ if the preceding pulse was + and with the sequence 000-+0+- of the preceding pulse was -, where… (Read More →)

Abbreviation for bipolar with eight-zero substitution. A T-carrier line code in which bipolar violations are deliberately inserted if user data contains a string of 8 or more consecutive zeros.
Note 1: B8ZS is used to ensure a sufficient number of transitions to maintain system synchronization when the user data stream contains an insufficient number of "ones" to do so.
Note… (Read More →)

In transmission systems, the aggregate of crosstalk induced in a given line by all other lines.

Synonym trapdoor.

1. A direct connection between the output of a transmitting device and the input of an associated receiving device.
Note: When used for equipment measurements or testing purposes, such a back-to-back connection eliminates the effects of the transmission channel or medium.
2. A direct connection between the output of a receiving device and the input to a transmitting device.
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1. The high-traffic-density connectivity portion of any communications network.
2. In packet-switched networks, a primary forward-direction path traced sequentially through two or more major relay or switching stations.
Note: In packet-switched networks, a backbone consists primarily of switches and interswitch trunks.

1. In Web pages, an image or color, usually defined in HTML, that serves as the underlying color or imagery for a Web page.
Note: Browsers may also be configured to dictate backgrounds.
2. In computer display systems, the underlying color or imagery for the main screen or for the fundamental window of a computer's operating system.