We present the first results of a 3D numerical modeling of linear MHD wave propagation in a realistic sunspot model. In our simulations, a piston located at the base of the photosphere generates waves with a certain period. The ratio between the acoustic and the Alfven speed, cS /vA, decreases from much larger than one at the photosphere to much lower than one in the chromosphere in our simulation domain. Waves propagate through the region where cS << vA, where mode transformation is observed. At a somewhat higher region, where cS = vA, the fast (magnetic) mode reflects back to the photosphere due to the vertical and horizontal gradients of vA. The slow (acoustic) mode propagates to the upper layers and increases its velocity amplitude. Unlike the 2D simulations, the Alfven mode is also generated by the piston and experiences transformations at the cS = vA layer. The behaviour of this mode requires further study.