VOIP Based Of DSP5402

IP telephone is a telephone operation according to the direction of internet protocol. The Chinese translation is network telephone or Internet telephones. It is a kind of new correspondence technique that using Internet as speech deliver medium to realize speech correspondence. Because of its cheap correspondence expenses, we call it cheap telephone. Network telephone, Internet telephone, economic telephone or cheap telephone. These are different names of IP telephone, in fact the essence meaning is same. Now the most extensive and scientific calling is IP telephone. It is taken more and more people's attention because of its low cost.This text will expatiate research process of a kind of IP telephone (free communication machine) based DSP5402. We could complete dialing telephone number and receiving call by family fix telephone via this machine, then complete speech via internet. This machine could communicate with family fix telephone , mobile telephone,IP telephone(other free communication machine). The method of using is alike as common telephone. In this paper, we discuss the design of free communication machine and didn't discuss the transmission of signal and settings of gateway.This design adopt 16 bits CPU-DSP5402, could realize the detect of the telephone's push and hang, decode of telephone key number, restore the IP number and telephone number. We could decode the voice signal via CODEC chip and compress the signal in G.723 mode, and last transmit the signal to internet.The point of this paper is the design of hardware, include circuit design of DSP (power supply , power supply detect , expanding of RAM&ROM) , detect of telephone push and hang , interface and program between CODEC chip and DSP, interface and program between internet chip and DSP. In this paper, we also discuss G.723 and SIP protocol in academic.In the last of this paper, we expound the method of hardware debug. All the parts of hardware have been passed through debugging. G.723 and SIP protocol have been passed in computer.