Glossary (U)

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UCF (UNREGISTRATION CONFIRM MESSAGE)
A RAS message that a Gatekeeper or an endpoint sends accepting the URQ.

UDP (USER DATAGRAM PROTOCOL)
A transport protocol within the TCP/IP protocol suite that is used in place of TCP when a reliable delivery is not required.

UE (USER EQUIPMENT)
Equipment at either end of a communications link that links to the network, otherwise known as endpoints.

UMA (UNLICENSED MOBILE ACCESS)
Former name for the Generic Access Network (GAN), describes a telecommunication system allowing seamless roaming and handover between local area networks and wide area networks using the same dual-mode mobile phone.

UMTS (UNIVERSAL MOBILE TELECOMMUNICATIONS SYSTEM)
One of the third-generation (3G) mobile phone technologies. It uses W-CDMA as the underlying standard, is standardized by the 3GPP, and represents the European/Japanese answer to the ITU IMT-2000 requirements for 3G Cellular radio systems.

UNICAST
An addressing form for sending information to a single destination, in contrast to broadcast or multicast where packets are addressed to more than one destination.

UPLINK
A unidirectional radio link for the transmission of signals from a UE to a base station, from a Mobile Station to a mobile base station or from a mobile base station to a base station.

URL (UNIFORM RESOURCE LOCATOR)
An Internet address. The address that defines the route to a file on a computer connected to the Internet.

USER AGENT
Any software or device that acts on behalf of a user, interacting with other entities and processing resources.

USIM (UNIVERSAL SUBSCRIBER IDENTITY MODULE)
An application for UMTS mobile telephony networks residing on the UICC smart card used for accessing services provided by mobile networks, which the application is able to register on with the appropriate security. Stores user subscriber information, authentication information and provides storage space for text messages.

UTRAN (UNIVERSAL TERRESTRIAL RADIO ACCESS NETWORK)
A conceptual term identifying that part of the network which consists of RNCs and Node Bs between Iu and Uu interfaces.