The mean spherical approximation (MSA) was used to investigate the phase behavior of charged colloidal systems with and without added salt. The competition between cohesive Coulomb interactions and stabilizing entropic and hard-core interactions controls the stability of the system and under certain circumstances, a liquid-gas-type phase transition can occur. The critical parameters and phase diagrams in the MSA obtained via the internal energy path, are compared with two-component Monte Carlo simulations and other theoretical approaches.