In recent years, massively multiplayer online games (MMOGs) have become more and more popular. Many techniques have been proposed to enhance the experience of using MMOGs, such as realistic graphics, vivid animations, and player communication tools, etc. However, in most MMOGs, communication between players is still based on text, which is unnatural and inconvenient. In this paper, we propose the concept of AOI voice chatting for MMOGs. The term AOI stands for the area of interest; a player in the MMOG only pays attention to his/her AOI. By AOI voice chatting, a player can easily chat by voice with other plays in the AOI. This improves the way players communicate with one another and provides a more realistic virtual environment. We also propose two peer-to-peer schemes, namely QuadCast and SectorCast, to achieve efficient AOI voice chatting for MMOGs. We perform simulation experiments to show that the proposed schemes have reasonable end-to-end delay and affordable bandwidth consump...