To detect the presence of at least one other terminal in a data session (e.g., an RTP session), terminal a generates a request to solicit a response from each terminal, forms an APP packet in RTCP for the request, encapsulates the APP packet in at least one IP packet, and sends the IP packet(s) to the other terminal(s). Terminal a then monitors for a response from each terminal to which the request is sent. Terminal a declares a terminal to be present in the data session if a response is received from that terminal. Terminal a may send one or more additional requests to each terminal from which a response is not received. Terminal a declares a terminal to be absent from the data session if a predetermined number of (e.g., two) requests have been sent to that terminal and a response is not received from the terminal.