Speech has been considered to be the most important component for human to communicate. Speech coding is the act of converting the speech signal in a more compressed form, which can be transmitted with less numbers of bits. It is nearly impossible to access unlimited bandwidth of a channel each time we send a signal, so there is a need to compress speech signals. Speech compression is required in the fields of long distance communication, high-quality speech storage, and message encryption having. Speech coding is the lossy type of coding, which means that the output signal does not exactly sound like input. In this paper different speech coding techniques namely Waveform Coding, Subband Coding And Linear Predictive Coding are discussed. Analysis of Differential Pulse Code Modulation is done by varying number of bits using MATLAB R2010a.