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U Interface
n. The electrical interface between an ISDN telephone line and a network terminator (NT1) device.
U Interface, N.
The electrical interface between an ISDN telephone line and a network terminator (NT1) device.
U-Law
An International Telecommunication Union Telecommunication Standardization Sector (ITU-T) standard for sampling data by means of Pulse Coded Modulation (PCM). U-Law is most commonly used in North America and Japan.
U-interface
adj. Specifies an ISDN communications device that connects directly to an ISDN telephone line. A U-interface device contains its own network terminator (NT1).
U-interface, Adj.
An ISDN communications device that connects directly to an ISDN telephone line. A U-interface device contains its own network terminator (NT1).
UDP
User Datagram Protocol
UDP Port
A 16-bit number that allows multiple processes to use User Datagram Protocol (UDP) services on the same host. A UDP address is the combination of a 32-bit IP address and a 16-bit port number. Examples of well-known UDP ports are 7 (for Echo packets), 161 (for SNMP packets), and 514 (for Syslog packets).
UDP Queue
A queue containing unprocessed User Datagram Protocol (UDP) requests.
UNI
User-Network Interface. 1) An interface point between Asynchronous Transfer Mode (ATM) end users and a private ATM switch, or between a private ATM switch and the public carrier ATM network; defined by physical and protocol specifications in ATM Forum UNI documents. 2) A similar connection in a Frame Relay network . 3) The interoperability standard adopted by the ATM Forum to define connections between users or end stations and a local switch.
UNIX
A multiuser, multitasking operating system originally developed by AT&T Bell Labs that runs on a wide variety of computer systems.
UNIX To UNIX Copy Program (UUCP)
An application program developed in the mid 1970抯 for Version 7 UNIX that allows one UNIX time sharing system to copy files to or from another UNIX time sharing system over a single link.
URL
Uniform resource locator. The address of a file (resource) accessible on the Internet. The type of resource depends on the Internet application protocol. For the World Wide Web's protocol, the Hypertext Transfer Protocol (HTTP), the resource can be an HTML page, a program such as a Java applet, or any other file supported by HTTP. The URL contains the name of the protocol required to access the resource, a domain name that identifies a specific computer on the Internet, and, if necessary, a path to the resource on the computer. The URL for Lucent Technologies, for example, is http://www.lucent.com.
UTP
Unshielded Twisted Pair
UTP cable
Unshielded Twisted Pair cable. Two paired wires with wire twisted two or more times per inch to help cancel out noise.
UUCP
UNIX-to-UNIX Copy Program. Interactive communication system for connecting two UNIX computers to send and receive data.
UUI
User-to-user identification. A field within ISDN protocol which can provide end-to-end information exchange (telephone number, credit card number, login ID, etc.)
Unicast Network
A network in which a router sends packets to one user at a time.
Unified Messaging
A platform that lets users send, receive and manage all email, voice and fax messages from any telephone, PC or information device. By linking to a consumer's e-mail account, for example, one component of unified messaging -- Lucent's Message Notifier solution -- immediately and proactively alerts users via their voice/fax mailbox that they have received e-mail.
Universal Asynchronous Receiver/Transmitter (UART )
A UART is a chip that provides a RS-232C data terminal equipment (DTE) interface to a device, enabling the unit to communicate with its attached serial devices.
Universal Time
The Greenwich Mean Time.
Unshielded Twisted Pair Cable
UTP cable consists of two wires twisted two or more times per inch in order to help cancel out noise. The entire cable has no covering. UTP cable is typically used in telephone lines for voice service, ARCnet networks, 10Base-T Ethernet networks, and particular sections of token ring networks.
Unspecified Bit Rate (UBR)
UBR is an asynchronous transfer mode (ATM) service class that handles bursty LAN traffic, as well as data that is tolerant of delays and cell loss. UBR is a best-effort service that does not specify bit-rate or traffic values, and offers no Quality of Service (QoS) guarantees.
Upstream Path
The path a call takes from the end user抯 home to the carrier抯 central office (CO).
User Datagram Protocol (UDP)
UDP is a transport-layer protocol that provides connectionless service without packet acknowledgment.
User-Network Interface (UNI)
The point at which users connect to the network.
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