The present invention relates to a Push to talk Over Cellular [PoC] Server for providing PoC communication services in mobile radio communications system, the PoC Server being arranged to perform at least one Controlling PoC Function for a PoC Session between PoC Clients in mobile terminals. The PoC Server is characterized in that it is arranged to: receive a first information indicating the PoC Session priority order for the PoC Session for each of the PoC Clients participating in the PoC Session; receive a second information, if any one of the PoC Clients is also participating in other simultaneous PoC Sessions, indicating the PoC Session priority order for the other simultaneous PoC Sessions for each of the PoC Clients participating in the other simultaneous PoC Sessions; store the first and second information for enabling control of the transmission of Media in the PoC Session based on the first and second information. The present invention also relates to a method, a mobile terminal comprising a PoC Client and a method thereof, a mobile radio communications system and a computer program product.