In this work, we present a further development and analysis of the Original UNIFAC-CI models for the prediction of vapor-liquid equilibrium (VLE) and solid-liquid equilibrium (SLE) for a wide range of mixtures. Three sets of atom interaction parameters (Alps) have been regressed. For the first two sets, only VLE experimental data were used in parameter estimation. In the first set, no weighting factors were used for each of the VLE data in the objective function when regressing the AlPs. However, for the second set, the AlPs have been regressed using the so-called Q(VLE) quality factors obtained for each of the VLE data from a quality assessment algorithm (consistency tests) as weighting factors in the objective functions. For the third set of parameters, SLE and VLE data were used in the regression of AlPs. The result of the correlations in terms of deviations errors and predictions using these three sets of regressed parameters are presented, compared and discussed. The significance of adding the Q(VLE) values and SLE systems in the regression of the AlPs are also highlighted. UNIFAC is a model that can be in principle used for both VLE and SLE (as well as other types of phase behavior) calculations. The range of applicability of the predictive UNIFAC-CI is investigated and it is shown to what extent the Original UNIFAC-CI model can successfully predict SLE especially when the needed parameters are missing. (C) 2014 Elsevier B.V. All rights reserved.