A user equipment, UE, (150, 810) for performing communication in a wireless communication system supporting a circuit switched fallback, CSFB, service, comprising: a transceiver (203, 503) configured to transmit and receive a signal over a communication system switched from among a first communication system and a second communication system; a measuring receiver (207, 507) configured to receive a signal for measuring a channel status from the second communication system upon initiation of a CSFB process as a voice call occurs and measure the channel status from the second communication system; and a controller (211, 511) configured to control the transceiver to transmit, to the first communication system, a radio resource control, RRC, connection request message including information indicating that measurement on the channel status of the second communication system is being performed, to receive, from the first communication system, an RRC connection setup message including information for instructing to report a measurement result on the channel status of the second communication system, to transmit, to the first communication system, an RRC connection setup complete message comprising the measurement result on the channel status of the second communication system, to receive, from a base station of the first communication system, a command to switch to the second communication system, and to connect the voice call over the second communication system, wherein the command to switch to the second communication system is generated based on the measurement result on the channel status of the second communication system. a transceiver (203, 503) configured to transmit and receive a signal over a communication system switched from among a first communication system and a second communication system; a measuring receiver (207, 507) configured to receive a signal for measuring a channel status from the second communication system upon initiation of a CSFB process as a voice call occurs and measure the channel status from the second communication system; and a controller (211, 511) configured to control the transceiver to transmit, to the first communication system, a radio resource control, RRC, connection request message including information indicating that measurement on the channel status of the second communication system is being performed, to receive, from the first communication system, an RRC connection setup message including information for instructing to report a measurement result on the channel status of the second communication system, to transmit, to the first communication system, an RRC connection setup complete message comprising the measurement result on the channel status of the second communication system, to receive, from a base station of the first communication system, a command to switch to the second communication system, and to connect the voice call over the second communication system, to transmit, to the first communication system, a radio resource control, RRC, connection request message including information indicating that measurement on the channel status of the second communication system is being performed, to receive, from the first communication system, an RRC connection setup message including information for instructing to report a measurement result on the channel status of the second communication system, to transmit, to the first communication system, an RRC connection setup complete message comprising the measurement result on the channel status of the second communication system, to receive, from a base station of the first communication system, a command to switch to the second communication system, and to connect the voice call over the second communication system, wherein the command to switch to the second communication system is generated based on the measurement result on the channel status of the second communication system.