Reversible 'liquid-vapour' like transitions and irreversible coagulation in charge-stabilized colloidal dispersions are studied using a one-component macroparticle framework with a conventional DLVO interaction potential. The spinodal and coexistence curves are calculated as a function of salt concentration using thermodynamic perturbation theory-specifically the random-phase approximation using firstly hard spheres and then sticky hard spheres as reference systems. With the hard spheres, the hard-core location varies between the first and second zero of the DLVO potential. In the case of the sticky hard spheres, the hard core is located at the first zero of the DLVO potential; this models the deep narrow primary minimum of this potential. The irreversible coagulation is distinguished from the reversible transition by the flattening of the coexistence curve at a value of salt concentration above the range over which the 'liquid-vapour' transition takes place.