The reliability of a charge pumping (CP) technique proposed recently, which allows the extraction of the Si–SiO2 interface trap concentration profiles in metal-oxide-semiconductor transistors, from fast to slow traps, is discussed. The shape of the trap concentration profiles measured, the values of the trap cross section extracted, and the integration of the trap profiles, which should give the interface trap density obtained using the conventional CP technique, are discussed with regard to the trap filling function variation and to surface-potential fluctuations. Then, the influence, on these profiles, of both carrier emission, which is neglected in the model used for calculating the profiles, and of the source and drain regions (S/D-R) of the devices, where the threshold and flatband voltages are different from those in the central region of the channel, is investigated. It is shown that carrier emission does not impact on the trap profiles and that the trap time constant distribution measured does not originate from the S/D-R of the devices. A way to detect a significant contribution of these regions to the charge pumping current measured is proposed. Finally, a comparison with noise spectroscopy is carried out. The results obtained using the two techniques agree very well.