Method of transiting rrc state into idle state of user equipment and system therefor and the user equipment

A method for transferring a UE(User Equipment) from an RRC(Radio Resource Control) state to an idle state, a system for the same, and a terminal therein are provided to effectively cope with an increase in the current consumption of a UE in case RRC connection release is delayed or not attempted though there is no packet data traffic any more in a cell_FACH(Forward Access CHannel) state. If an SCRI(Signaling Connection Release Indication) transmission condition is satisfied(501), a UE transmits an SCRI message to an RNC(Radio Network Controller)(503). Receiving the SCRI message, the RNC transmits an Iu release request message to an SGSN(Serving GPRS Support Node)(505). Based on a cause value contained in the received IRR message, the SGSN transmits an Iu release command message to the RNC(507). Receiving the Iu release command message, the RNC releases Iu signaling connection resources, and transmits an Iu release complete message to the SGSN(509). Then the RNC transmits an RRC connection release message to the UE(511). Receiving the RRC connection release message, the UE transits to an idle state from an RRC state while transmitting an RRC connection release complete message to the RNC(513).