Method and system for processing an ad hoc group participating information in poc system

A method and a system for processing PoC(PTT(Push To Talk) over Cellular) ad hoc group session information using an RTCP connection message are provided to allow a reception PoC server to check whether a user participates in a session regardless of an answer mode of a reception PoC client. When a session invitation message including ad hoc group inviter information is received from a transmission network, a PoC server generates a connection message including the inviter information and an AAO(Auto-Answer Override) request parameter, transfers the connection message to a reception PoC client, and performs a PoC session procedure according to an answer received from the PoC client. When the connection message is received, the PoC client sets a manual answer mode regardless of a currently set answer mode, transfers the inviter information included in the connection message to a PoC user, and transfers an answer message including whether or not the PoC user participates in the session inputted from the PoC user to the PoC server.