Abstract: An efficient G.729ab and G.723.1 unin multichannel codec is designed on TMS320C6203. Both of the compression algorithms can be realize simultaneously on different channels of the codec. Pure assemble instruction and C language mixed programming is used to improved the effectiveness. The unin codec and supply 31 G.729ab channnels or 22 G.723.1 channnels. Multichannel Buffered Serial Port of TMS320C6203 is disposed as E1 interfacet to PSTN. Host Processor Interface of TMS320C6203 is designed to provied a Real-time protocol connection. This unin codec can be used on Media gateway conveniently.