The synergy between frequency and phase modulation (FPM) using trellis-coded modulation (TCM) leads to greater gains than can be achieved using conventional TCM/MPSK modulation. An iterative structure is introduced into a TCM/FPM scheme to give a new scheme, the turbo TCM/FPM scheme. Simulation results show that the new scheme can achieve a significant performance improvement with respect to the turbo TCM 8PSK and TCM/FPM schemes, respectively, for a DS/SSMA system over a multipath Rician fading channel.