System and method for requesting and grantting poc user media transmission authority

A method for requesting and granting PoC(PTT(Push To Talk) over Cellular) user media transmission authority and a system are provided to enable a PoC client to transmit an MBCP(Media Burst Control Protocol) request message after storing the request message, without a PoC user requesting the messsage again even though a request for media transmission authority is denied, thereby shortening a time for media transmission request. A PoC client transmits an MBCP request message according to a user's request(400). A PoC server checks whether the current state corresponds to a media transmission deny condition, and if so, the PoC server transmits a media transmission deny message including at least one of media transmission timer time information and retry after timer time information to the PoC client(402,404). The PoC client drives a media transmission timer and a retry after timer by using each piece of the time information, and if one of the timers, which has a longer time, expires, the PoC client retransmits the MBCP request message.