The giant magnetoimpedance effect is related to the great sensitivity showed by ultra-soft ferromagnetic compounds to an external magnetic field during a high frequency excitation. Because of the skin effect the current distribution in the sample is not uniform and the current density concentrates in a thin layer around the sample. The measurements of the complex magnetoimpedance (instead of the modulus) allow us to find several processes present in the samples closely related to the dispersive behavior of the magnetic permeability and magnetostriction. Moreover, the plot of the phase angle versus frequency shows the presence of resonant contributions in the permeability according to the Bloch-wall movement equation.