|UI - User Interface
|Um - The air interface between the BTS and the MS in a GSM network
|UMTS - Universal Mobile Telecommunications System. A third-generation (3G) wireless communications technology and the next generation of GSM. UMTS is a wireless standard approved by the International Telecommunications Union and is intended for advanced wireless communications.UMTS uses WCDMA technology, and the two terms are often used interchangeably with each other.
|UPN - Universal Personal Number
|UPT - Universal Personal Telecommunications
|URL - Uniform Resource Locator; the addressing system of the Internet
|USIM - Universal Subscriber Identity Module; the 3G equivalent of the GSM SIM
|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
|Uu - The air interface between the Node B and the MS in a UMTS network.
|UWB - Ultra Wide Band