Patent ID: 8335197

Claim:
A method for transmitting Session Initiation Protocol (SIP) data by an idle mode User Equipment (UE) in a mobile communication Internet Protocol Multimedia Subsystem (IMS) system, the method comprising the steps of: delivering SIP data received from an upper layer in an idle mode to a Non Access Stratum (NAS) layer; setting a message type of a NAS control message, by the NAS layer, as a Long Term Evolution (LTE) connection request message comprising the SIP data; setting an indicator and length information of the SIP data in the NAS control message in front of a part where the SIP data is to be included, generating a single combined message by attaching the SIP data to the rear of the length information of the NAS control message, and delivering the generated single combined message to an Access Stratum (AS) layer; generating an AS control message by the AS layer, and generating an LTE connection request message by the AS layer by combining the generated combined message with the AS control message; sending a scheduling request to an Evolved Radio Access Network (E-RAN); and sending the LTE connection request message to the E-RAN using allocated radio resources in response to a scheduling response message received from the E-RAN.