In this paper, the intraframe and interframe correlation propeffie s are used to develop two efficient encoding algorithms for speech line spectrum pair (ISP) parameters. The first algorithm (2-D DCT) , which requires relatively large coding delays, is based on twodi mensional (time and frequency) discrete cosine transform coding te chniques; the second algorithm (DCT- DPCM), which does not need any coding delay, uses one-dimensional discrete cosine transform in th e frequency domain and DPCM in the time domain. The performance of these systems for different bit rates and delays are studied and a ppropriate comparisons are made. It is shown that an average spect ral distortion of approximately 1 dB sup 2 can be achieved with 21 and 25 bits/frame using the 2-D DCT and DCT-DPCM schemes, respecti vely. This is a noticeable improvement over the previously reporte d bit rates of 32 bits/frame and above [1], [2].