Abstract: 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.

Abstract: A first mobile device has two air interfaces. The first mobile device uses its first interface to transmit VoIP/VIP packets to a second device in a first session. If a quality of service decreases, then the first device causes a second session to be set up where the second session uses the second air interface. Both the first and second air interfaces are then used to communicate packets of a single media stream from the first device to the second device. The packets are transmitted in the first and second sessions in interleaved fashion, where the ratio of packets communicated in one session versus the other per unit time is adjusted in accordance with a quality of service afforded by one session versus a quality of service afforded by the other session. The second device orders the data payloads of the packets, thereby reconstructing the single media stream.

Abstract: A mobile communication device (for example, a cellular telephone) has one air interface for wireless communication with wireless LAN and another air interface for cellular telephone communication with a cellular telephone network. Initially, the communication device is used to transmit VoIP packets of a media stream to a target communication device in a first session across one of the air interfaces. It is then desired to use the other air interface. A spawn SIP message is communicated to the target, which returns a spawn identifier. The communication device sets up a second session by sending a SIP INVITE containing the spawn identifier to the target across the other air interface. Both sessions are active VoIP sessions. The target uses the spawn identifier to associate the first and second sessions. The flow of VoIP packets for the media stream is then switched from the first session to the second session.