Despite the single P-31 peak observed in solution, high-resolution solid-state P-31 NMR spectra of poly[bis(phenoxy)phosphazene] (PBPP) consist of two well-resolved peaks, whose intensities and positions show temperature dependence. Taking into account different characteristic spin dynamics, these two peaks are attributed to crystalline and amorphous parts of PBPP. It is shown that there exists a moderately fast spin diffusion between the two P-31 peaks. A close examination of the mixing-time dependence of the cross-peak intensity indicates an existence of the interface phase. The present experiments enable us to determine the temperature dependence of the ratio of amorphous, interface, and crystalline phases in the PBPP sample. Furthermore, the observed temperature dependence of the C-13 line widths of the side-chain group is analyzed, and the activation parameters of motion of the phenoxy group about its P-O bond are determined.