Multi-Tech Systems MT4X56USB manual

MultiModemUSB User Guide

USB: See Universal Serial Bus.

USBD: See Universal Serial Bus Driver.

USB Performance categories: Low Speed (Interactive Devices at 10-100 Kb/s); Medium Speed (Phone, Audio, Compressed Video at 500Kb/s - 10Mbp/s); High Speed (Video, Disk at 25-500 Mb/s)

V

V.25bis: An ITU-T standard for synchronous communications between a mainframe or host and a modem using HDLC or other character-oriented protocol.

V.54: The ITU-T standard for local and remote loopback tests in modems, DCEs and DTEs. The four basic tests are:

•local digital loopback (tests DTE send and receive circuits),

•local analog loopback (tests local modem operation),

•remote analog loopback (tests comm link to the remote modem), and

•remote digital loopback (tests remote modem operation).

Virtual Circuit: A logical connection. Used in packet switching wherin a logical connection is established between two devices at the start of transmission. All information packets follow the same route and arrive in sequence (but do not necessarily carry a complete address).

W

Wide Area Network (WAN): 1. A network that provides communication services to a geographic area larger than that served by a local area network or a metropolitan area network, and that may use or provide public communication facilities.

2.A data communications network designed to serve an area of hundreds or thousands of miles; for example, public and private packet-switching networks, and national telephone networks. Contrast with local area network (LAN).

Wide Area Telecommunications Service (WATS): A low-cost toll service offered by most long distance and local phone companies. Incoming (800 call service, or IN-WATS) and outgoing WATS are subscribed to separately, but over the same line.

X

X.25: ITU-T’s definition of a three-level packet-switching protocol to be used between packet-mode DTEs and network DCEs. X.25 corresponds with layer 3 of the 7-layer OSI model.

Y

Yellow Alarm: An error indication sent by the T1 device when it has not gotten a receive signal, or cannot synchronize on the receive signal received. Contrast “Red Alarm” and “Blue Alarm”.

Z

Zero Byte Time Slot Interchange (ZBTSI): A method for allowing 64 Kbps unrestricted user data (allowing all 0s in the user data). An alternative to (but not as popular as) B8ZS.

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