Methods and apparatus are described for transmitting and receiving data by a wireless transmit/receive unit (WTRU) over the control plane. The methods may receive data without the use of an Internet Protocol (IP) address. In an example method, a WTRU may enter an evolved packet system (EPS) mobility management (EMM)-registered control plane only (CPO) state after receiving an attach accepted message for CPO operation, and enter an EMM-deregistered state after receiving a detach message, a tracking area update (TAU) reject message or an attach reject message. In another method, a WTRU may switch between operational modes that use an IP address and a user plane to transmit and receive data, and the CPO mode.