The Raman spectra of DyPO4, under variable hydrostatic pressure at room- and low-temperature (110 K), have been studied. Crossing, with increasing pressure, of two modes in the frequency range of the internal-external border, is observed and discussed. At low temperature, the pressure dependence of the three highest-frequency internal modes is monitored, which exhibit a (dω/dP)-slope differing, well beyond the experimental error, from the corresponding room temperature slopes. At room temperature, all the expected modes are observed and are divided in two distinct groups on a "logarithmic derivative" vs. "peak-frequency" graph. This division is discussed in terms of the internal-external mode-character.