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We have studied by means of Raman spectroscopy the electron density in two different n-type InP samples with similar doping densities, obtained, respectively, by ion-beam implantation of 150 keV Si* and by uniform Sn doping during LEC growth. The Raman spectra recorded at 80 K display in both cases the L+ and L-phonon-plasmon coupled modes. For the homogeneously doped InP: Sn sample, a simultaneous fit to the L+ and L-peaks of a line shape model based on the Lindhard-Mermin dielectric function yields accurate values of the charge density. In the implanted sample, the nonuniformity of the charge distribution substantially broadens the L+ modes, but the line shape fit to the L-mode still yields an average value of the electron density in the region probed by the laser beam.