For rapid indoor 3D localization of smartphones, a new method called Frequency Division Multiplexing Phase Accordance Method (FDM-PAM) is proposed. The method uses a beat called a sync pattern composed of a pair of sinusoidal waves whose frequencies are slightly different, which is the same way as our original ultrasound ranging technique called the Phase Accordance Method (PAM). By generating multiple sync patterns whose central frequencies are different and transmitting each of them from different speakers, FDM-PAM conducts time-difference-of-arrival (TDOA) multilateration. In the current implementation of FDM-PAM, four sync patterns are generated by using two out of eight sinusoidal waves whose frequencies range from 14.75 kHz to 18.25 kHz (frequency interval: 500 Hz). Through experiments using four speakers in short baseline intervals (10-14 cm), it is confirmed that FDM-PAM achieves accuracy range around 10 to 30 centimeters using only a transmission of a short burst (4 ms), which indicates a sufficiently rapid indoor localization for smartphones