Rhombohedral and monoclinic modifications of the Li3In2(PO4)(3) compound have been studied by X-ray diffraction, infrared (i.r.) analysis, Raman light scattering, differential thermal analysis (DTA), differential scanning calorimetry (DSC) and impedance spectroscopy, in a wide temperature range of 290-600 K. Analysis of the data allows the suggestion that the superionic phase transition, observed in these materials in the temperature interval 370-385 K, belongs to Faraday type phase transformations. PO4 tetrahedra, which are a partition of the (In2P3O12)(300)(3-) rigid skeleton, have been found deformed. This seems to be due to an ordered lithium ion-vacancy distribution in the low temperature, non-superionic, polymorphs. With increasing temperature these deformations disappear, This disappearance can be caused by a decrease of the correlation length of the lithium ion-vacancy order.