A method and system for call setup in an evolved third generation (3G) radio access network are disclosed. A wireless transmit/receive unit (WTRU) sends its identity to a core network (CN) for call setup when the WTRU is in an RRC_disconnected state. The CN verifies the identity and sends an authentication vector to the WTRU. The WTRU sends a service access request message including an authentication response to the CN via a Node-B. The Node-B performs an admission control. The CN attaches the WTRU if the authentication response is same to an expected response. The Node-B then allocates radio resources to the WTRU. The Node-Bs may be directly connected, or may be connected to a control plane server which performs admission control. When the WTRU is transitioning from an RRC_idle state to an RRC_connected state, the WTRU may or may not need to re-authenticate again.