Videoconferencing means communicating to one or multiple remote parties by transmitting both audio and video. To establish a videoconference, all involved parties must agree on the used audio/video codecs, determine how much network bandwidth to use, and much more. Of course, all involved clients must use the same protocol, or they will not understand each other. There exist several protocols for videoconferencing and VoIP. XMeeting supports the two standards H.323 and SIP. Both are considered an Open Standard and are supported by a wide variety of videoconferencing and VoIP equipment.

Open Standards have the benefit of being accessible to everyone. Anyone can build a device conforming to the standard if he/she wishes to do so. Thus, H.323 and SIP are defined independent of any manufacturer, hardware or software - in contrast to proprietary solutions like e.g. Skype.

H.323 and SIP provide means for establishing and managing a session between the involved endpoints. They also provide possibilities for negotiating which codecs to use in a session. Another common feature is the possibility to use a kind of directory server for user address lookup. This allows to call a user by entering a name or phone number instead of having to know the user's current IP address. This address or phone number works worldwide regardless of where the user is located at the moment.
For both protocols exist gateways that can bridge into the Public switched telephone network (PSTN)

A short Overview of H.323 and SIP is presented on the next page.