Abstract: Methods, systems, and mediums for enabling clients to traverse firewall and Network Address Translation (NAT) installations by using probe packets between servers and clients to communication the addresses modified by the NAT.

Abstract: A method and apparatus for synchronizing sound and images in a real-time multimedia communication, such as an audio-video telephone call, through a network gateway, when the source and/or the destination of the audio signals, and optionally also the video signals, are from and/or to separate audio and video communication devices.

Abstract: An apparatus for communicating video frames from a source having a video input means to a destination having a visual display unit during the course of a telephone conversation. A first user can use a first computer communication means to make a first connection to a service provider. The service provider or first user then initiates a telephone call from the first to the second telephone via the service provider and the first and second communication paths. A second user can then use the second computer communication means to make a second connection to the service provider. Caller-id data is communicated between each of the first and second users and the service provider so that the service provider can correlate both the call and the first and second connections with each other. At least one video image is uploaded from the video input means to the service provider, and then downloaded to one of the computers.