Currently, more and more enterprises adopt the Voice over IP (VoIP) technology to replace their traditional circuit switching infrastructure in order to reduce the cost of their telephony services. The most frequently used VoIP solutions are made up of stand-alone software - usually complex and requiring extra hardware in a local area network. Some VoIP service providers offer Website based or plug-in based solutions, which are, however, difficult to integrate with other applications by the end user. Web services provide functionality over the Internet using various standards like XML and HTTP, independently of the operating system and programming language. In this paper, we propose a framework for Voice over IP based on Web services. Service providers using this framework can offer their customers a protocol-neutral Web service interface, thus enabling the deployment of a general and integrated VoIP solution. Because of the simplified logic, a client in this system is easy to implement and can communicate with clients in other systems without additional local hardware for VoIP.