In this paper I'd like to share our experience related to broadcasting in silent way using Wi-Fi P2P. In general, to broadcast data via Wi-Fi network all devices should be connected to access points and only connected devices can broadcast and receive data. Even in Wi-Fi P2P which is a standard of Wi-Fi Alliance at least one device should be a group owner and other devices should participate in the group as clients. So we propose connectionless messaging where devices can broadcast data without any association or connection. In connectionless messaging devices can broadcast data to undiscovered devices and receive data from undiscovered ones. Multiple devices can send data to unknown devices. And also, each device can receive data from multiple undiscovered devices using Wi-Fi P2P. Because we utilize the vendor specific field of Wi-Fi P2P frame, the connectionless messaging does not harm existing Wi-Fi P2P devices and services. In this paper we'll show you how we made connectionless messaging and how the connectionless messaging can be taken advantage of.