With the development of multimedia technology, and the real-time communication technology, people's requirement for real-time audio and video communication is higher and higher. The WebRTC technology emerges and occupies the market quickly based on its powerful audio and video processing engine, which has a huge impact on multimedia communications industry. WebRTC JSEP provided, however, can only perform simple media link function. It is required to combine with other modules or signaling protocol to do a complete application in the communication of enterprise. This paper focuses on the WebRTC communication with the SIP, and in the iOS terminal it designs and implements a kind of application layer gateway based on WebRTC technology. Finally, the feasibility and practicability of the gateway is verified with experiments.