User guide

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Glossary
Multi-Tech Systems, Inc. MultiVOIP User Guide
U
UART (Universal Asynchronous Receiver/Transmitter) (pronounced "you art"): A chip that transmits and receives data on the
serial port. It converts bytes into serial bits for transmission, and vice versa, and generates and strips the start and stop bits
appended to each character.
UNIX: An operating system developed by Bell Laboratories that features multiprogramming in a multi-user environment.
Unshielded Twisted Pair (UTP): Telephone-type wiring. Transmission media for 10Base-T.
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 wherein 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).
Z
Zone: A collection of all terminals, Gateways, and MCUs managed by a single Gatekeeper. A zone must include at least one
terminal and can include LAN segments connected using routers.