U
UI
User Interface
Um
The air interface between the BTS and the MS in a GSM network
Uu
The air interface between the Node B and the MS in a UMTS network.
UMTS
Universal Mobile Telecommunications System; the European entrant for 3G; now subsumed into the IMT-2000 family as the WCDMA technology.
UPN
Universal Personal Number
UPT
Universal Personal Telecommunications
URL
Uniform Resource Locator; the addressing system of the Internet
USO
Universal Service Obligation
UTRA
Universal Terrestrial Radio Access; the air interface component of WCDMA.
UTRAN
Universal Terrestrial Radio Access Network; the UMTS radio access network comprising the RNC, Node B and the air interface
USIM
Universal Subscriber Identity Module; the 3G equivalent of the GSM SIM
UWB
Ultra Wide Band
