Although humanity has made great progress in economy and science, the problem of public security is going downhill. If the life and property of people could not be safeguarded, more problems will arise. A home is a place where people can have a rest after work, so people have a thirst for safe and genial home. Therefore, the need of the HSS ( Home Security System ) is to grow with time passing. In spite of the number of security service firms being over two hundred in Taiwan at present, and that these firms have generally provided HSS, the HSS business is still quite limited due to higher charge and questionable quality of the security service personnel. Besides, the climate of DIY ( Do It Yourself) is hot recently, the market of the DIY HSS is growing fast. The advantages are cheap price, flexibility, privacy, and pleasure of DIY. But the reliability of the products off shelf is unstable and their functionality is not satisfactory. Thus the consumer encounters the perplexity when buying the product. Therefore, we have developed a HSS that is based on the PSTN (Public Switched Telephone Network.). The benefits are low-priced, stability and easy installation and usage. It is another choice for the HSS. In this paper, we describe the framework and functionality of the HSS based on the PSTN.