The Research And Implementation Of Miniature VoIP Module

VoIP(Voice over Internet Protocol) refers to that voice transmit over IP network. Formore than a decade of research and development, VoIP already has been a relatively maturetechnology. And now VoIP is widely being used in the telecom network and the computernetwork. However, with the growing demand for VoIP applications, the problem that howto design a more low-cost VoIP product becomes more and more difficult to be solved byVoIP equipment suppliers. Considering that there are still a large number of PSTNtelephones in the market and the price of IP phone is still high. In this paper, a low-costminiature VoIP module that could be used to modify an ordinary PSTN phone to aVoIP-enabled IP phone is designed.Firstly, this paper expatiate the background and the current status of IP phone, anddraws a comparison between IP phone and PSTN phone. At the meantime, the principles ofIP phone, the architecture and the key technologies of the VoIP system are introduced.Then the network elements, the workflows and the messages of SIP are also described indetails. After that a SIP-based miniature VoIP module design is proposed and a detailedintroduction to the hardware circuit design and the miniature of VoIP module is given. ThePSTN phone modified by the miniature VoIP module has been tested. The result of the test,shows that the miniature VoIP module could be used to modify an ordinary PSTN phone toa VoIP-enabled IP phone. Finally, a summary of the paper is made and the next step of thework to be done is discussed.