Micro-Raman measurements and Rietveld refinements of x-ray data have been carried out in the superconducting system with , to delineate the effect of the excess doping on the Raman active phonons and especially on the characteristics of the plane oxygen modes. The increase of the Cu(2)-O(4) bond length with increasing Ca concentration induces a much smaller decrease in the frequency of the phonon of the apical O(4) atom than the rare earth substitutions for Y. The frequency of the in-phase vibrations of the plane oxygens decreases slightly with increasing Ca content, but remains well above the lowest value that has been reported for the oxygen overdoped pure compound, suggesting that the softening of this mode observed in those samples may not be attributed to the addition of carriers. The frequency of the out-of-phase -like vibrations of the plane oxygens is not affected by the substitution, but the width of the corresponding phonon increases considerably. This increase is due to the appearance of another mode of symmetry that could correspond to a hypothetical phase separated from the pure YBCO phase.