Business telecommunications and IT systems

An ISDN term.

The interface between the subscbiber's premises ISDN termination point and the local telephone exchange.

Controlled by the PTOs

User Datagram Protocol.

One of the core members of the Internet Protocol Suite.

With UDP, computer applications can send messages as datagrams to other hosts on an IP network without requiring prior communications to set up special transmission channels or data paths.

UDP uses a simple transmission model but without implicit hand-shaking dialogues for providing reliability, ordering, or data integrity. Hence, UDP is an unreliable service and datagrams may arrive out of order, appear duplicated, or go missing without notice.

UDP's stateless nature is also useful for servers answering small queries from huge numbers of clients. Unlike TCP, UDP is compatible with packet broadcast (sending to all on local network) and multicasting (send to all subscribers).

Common network applications that use UDP include: the Domain Name System (DNS), streaming media applications such as IPTV, Voice over IP (VoIP), Trivial File Transfer Protocol (TFTP) and many online games.

Ultra High Frequency.

see Radio Spectrum.

Ultra Low Frequency.

see Radio Spectrum.

A cellular radio term. Universal Mobile Telecommunications System.

The European third generation wireless standard.

According to the GSM association, UMTS will offer a wide range of voice, data and multimedia services.

Data rates will reach from 114 to 2,000kbit/s (2Mbit/s) depending on whether the user is stationary or in motion.

United Nations.

A telephony term.

The message ‘Unavailable’ is delivered when a call comes from a network that does not support CLI and BT Call Return type services.

This could be from another network such as some mobile networks, a caller using a Chargecard, or from calls where the message ‘Payphone’, ‘International’, or ‘Operator’ is delivered.

see Withheld.

A Frame Relay term.

User to Network Interface.

A Uniform Resource Identifier is a string of characters used to identify a resource on the Internet.

A multi-user operating system designed for use on mini computers, but now becoming more popular on PCs.

Usually aimed at Corporates and large network users.

A Port used to link hubs.

The speed at which data can be uploaded to the Internet connection.

BT refer to upload as Upstream.

see Download.

A BT term for Upload.

Typically indicates the data flow from a User to the Internet.

Uninterruptible Power Supply Unit.

In effect, the term reflects that a power failure cannot uccur, usually by having large batteries to provide power to a piece of equipment in case of mains failure, therefore without a break in supply.

Uniform Resource Identifier.

Uniform Resource Locator (URL).

A Uniform Resource Identifier which specifies a specific location and resource and how to retrieve it.

The well known use of URLs is the addresses of Internet web pages on the World Wide Web, such as http://www.dupre.co.uk

Universal Serial Bus.

A slot in a PC from which up to 127 peripherals can be attached in a daisy-chain manner.

An Internet term, also known as Newsgroups.

A large number of discussion forums on different subjects. Anyone can join a group to listen and contribute to a discussion.

A BT Digital Select Service.

User to User Signalling (UUS) was launched on 21st September 1998, and allows a subscriber to exchange a limited amount of data with another subscriber using the D channel, whether the telephone call has been connected or not.

This service is available on ISDN BRA, only. Data can be sent at either 500bit/s continuously, or in bursts up to 2.4kbit/s for 2 seconds, providing 128 octets.

UUS1 allows this before the call is connected - during the ‘set up’ phase of the call; before connection and charging begins.

UUS3 allows this whilst the call is connected - during the ‘active’ phase of the call - whilst the call is connected.

Unshielded Twisted Pair cable.

Contains one or more pairs of cables.

The two wires of each pair are twisted around each other at a pitch of 6 twists per inch to minimise the effects of electromagnetic radiation.

Made to category 3 or category 5.

The former is used for telephone system cabling, the latter for computer networks.