A method and apparatus are described for providing non-packet switched service to a target radio access technology (RAT) network. A circuit switched (CS) service notification message is received by a wireless transmit/receive unit (WTRU). If the WTRU has been allocated a valid temporary mobile subscriber identity (TMSI), a paging response message including the valid TMSI is transmitted after an inter-system change is performed from a source RAT network to a target RAT network. The CS service notification message is for terminating a CS call request. The source RAT network may be a long term evolution (LTE) network, and the target RAT network may be a third generation partnership project (3GPP) network. Alternatively, if the WTRU has not been allocated a valid TMSI, a paging response message including an international mobile subscriber identity (IMSI) that identifies the WTRU is transmitted after the inter-system change.