We analyze numerically the critical behavior of an absorbing phase transition
in the conserved transfer threshold process. We determined the steady state
scaling behavior of the order parameter as a function of both, the control
parameter and an external field, conjugated to the order parameter. The
external field is realized as a spontaneous creation of active particles which
drives the system away from criticality. The obtained results yields that the
conserved transfers threshold process belongs to the universality class of
absorbing phase transitions in a conserved field.Comment: 6 pages, 8 figures, accepted for publication in Phys. Rev.