A method, a server and a system for managing a session in walkie-talkie (“push-to-talk”) mode between terminals each of which has respective capacities for encoding and decoding voice and/or image signals. The terminals are logged onto the session via a server and a first wireless telecommunications network to which the terminals are connected and a second network to which the server is connected. The server comprises a data encoder/decoder. When a session is established at the request of a terminal, a sender terminal sends data encoded according to an initial type of coding to one or more receiver terminals that are connected via the server. The server receiving data encoded according to the initial type of coding then processes the data according to the respective capacities of the receiver terminals in order to ensure compatibility of the data encoded according to the initial type of coding and the data received by the receiver terminals, where applicable according to at least one type of coding other than the initial type of coding. The server then sends the processed data to the receiver terminals.