This paper proposes the world first complete voice call handover scheme between the 3G LTE and 3G CS systems. To achieve seamless handover, a powerful network entity called FW-MME is proposed. Features of the FW-MME contribute to reducing handover service interruption time; hence the resulting voice call handover performance is also improved. The evaluation result shows that the proposed FW-MME exclusively meets the strict service interruption time requirement which is smaller than 300 ms, whereas other conventional handover schemes spend more than twice large time in voice call handover.