The pressure and temperature dependent dielectric relaxation times are compared with the predictions of the model proposed by Avramov. Remarkable agreement is found in whole P and T plane. It was also pointed out that the tested model predicts no pressure effect on fragility and nonlinear character of pressure dependence of glass transition temperature. Our data provide also an assessment of the generalized Vogel-Fulcher-Tammann (VFT) law. However, it is inferred that the generalized VFT law is not able to accurately reproduce the surface described by experimental relaxation times. Additionally, isothermal data are analyzed by the pressure counterpart of the temperature VFT law. The isothermal data expressed in terms of the reduced relaxation time and reduced pressure form a master curve.