The Universal Mobile Telecommunications System (UMTS) as specified by the Third Generation Partnership Project (3GPP) was formally adopted by the ITU as a member of its family of IMT-2000 Third Generation Mobile Communication standards in November 1999. This paper provides some background to the UMTS standard and an overview of the system architecture. Some information about the current status of technology trials is provided as well as predictions for the services that future UMTS networks are likely to deliver to the end user.