We have studied the electrical activation of the Fe2+∕3+ trap in Fe-implanted InP by means of capacitance-voltage and deep level transient spectroscopy analyses. Five deep traps have been identified and we have characterized the concentration and depth distribution of the Fe2+∕3+ deep trap, located at EC–0.66eV. The InP substrate background doping, i.e., the Fermi-level position, plays a crucial role in the Fe activation process by setting an upper limit to the amount of Fe centers electrically activated as deep acceptor traps.