A semi-insulating bulk single crystal of silicon carbide is disclosed that has a resistivity of at least 5000 -cm at room temperature and a concentration of deep level trapping elements that is below the amounts that will affect the resistivity of the crystal, preferably below detectable levels. The compensating fiber is selected to completely compensate dispersion slope while only partially compensating total dispersion. The logic may cause voice messages to be stored in a device from the set of devices closest to a location from which the user has retrieved messages. A precoder sequence related to a subset of precoders present in a wireless device can be defined sequentially, cyclically shifted according to an identifier or one or more communications parameters, randomly, pseudo-randomly according to an identifier or one or more communications parameters, andor the like.