A PoC system, method, user equipment and server used for managing one or more media types supported in a PoC session opened between a PoC server and one or more PoC clients is provided. When at least one PoC client is engaged in a Open Mobile Alliance (OMA) Push-to-talk (PPT) over Cellular (PoC) multimedia communication service and is to be withdraw from a PoC session in which the PoC client is participating, a PoC server identifies and stores information about one or more media types that were negotiated to be usable between the corresponding PoC client and the PoC server when the corresponding PoC client joined the PoC session. Next, when the number of PoC clients using the identified one or more media types among remaining PoC clients participating in the PoC session is one or less, the PoC server determines that the identified one or more media types is no longer needed for the corresponding PoC session, and corrects the PoC session so as to not use the identified one or more media types. Accordingly, when the one or more media types will not be received by any PoC client in the PoC session the use of the one or more media types in the PoC session is discontinued, so that it is possible to prevent a transmission error of the corresponding one or more media types and to save resources allocated to the corresponding one or more media types.