<P> UTRAN (short for "Universal Terrestrial Radio Access Network") is a collective term for the network and equipment that connects mobile handsets to the public telephone network or the Internet . It contains the base stations, which are called Node B's and Radio Network Controllers (RNCs) which make up the UMTS radio access network . This communications network, commonly referred to as 3G (for 3rd Generation Wireless Mobile Communication Technology), can carry many traffic types from real - time Circuit Switched to IP based Packet Switched . The UTRAN allows connectivity between the UE (user equipment) and the core network . </P> <P> The RNC provides control functionalities for one or more Node Bs . A Node B and an RNC can be the same device, although typical implementations have a separate RNC located in a central office serving multiple Node Bs . Despite the fact that they do not have to be physically separated, there is a logical interface between them known as the Iub . The RNC and its corresponding Node Bs are called the Radio Network Subsystem (RNS). There can be more than one RNS present in a UTRAN . </P>

The interface that connects node b and rnc in umts is