  We analyse the role of partonic transverse motion in unpolarized
Semi-Inclusive Deep Inelastic Scattering (SIDIS) processes. Imposing
appropriate kinematical conditions, we find some constraints which fix an upper
limit to the range of allowed k_perp values. We show that, applying these
additional requirements on the partonic kinematics, we obtain different results
with respect to the usual phenomenological approach based on the Gaussian
smearing with analytical integration over an unlimited range of k_perp values.
These variations are particularly interesting for some observables, like the <
cos phi_h > azimuthal modulation of the unpolarized SIDIS cross section or the
average transverse momentum of the final, detected hadron.
