A digital switch module for a time division digital switching system includes an encoding law conversion memory and a control memory. The encoding law conversion memory has previously stored therein conversion data for converting between different types of encoding laws. For example, the A-law and .mu.-law encoding laws set forth in CCITT Recommendation G.711 can be converted by a digital switch module according to the present invention. The encoding law conversion memory includes a read only memory having regions for conversion between A-law and .mu.-law encoded data and for nonconversion of both A-law and .mu.-law encoded data. The control memory designates which of the regions in the encoding law conversion memory is to be used during each time slot, thus dynamically controlling whether data passing through the digital switch module is converted or not. The type of conversion or nonconversion designated by the control memory can be determined by the type of data, e.g., digitized voice signals may require conversion but non-voice signals will not be converted, and the channel path of the data, for example from an A-law encoded system to a .mu.-law encoded system.