Those of you who are not using videoconferencing technology at your meetings and events, please step to the rear. Nobody moved? Great--you're an in-touch, leading-edge bunch of managers, and you're smarter than the average bear.

Yet, isn't it true that even you sometimes feel your eyes glazing over as an AV supplier starts delivering his spiel? Wouldn't it be useful to know when somebody is trying to snow you? That's what Geek Speak is all about! Without further ado, here's Part I of the Geek Speak Guide to Videoconferencing:

Audio: The most important variable affecting the perceived quality of a videoconferencing experience. Use the best microphones and speakers you can buy, lease, or rent. Make sure that any in-house audio system is top-shelf, too.

Backplane: The back of the codec (see below), generously appointed with goesintos and comesoutas (those are technical terms). This is where you can plug in all sorts of auxiliary input and output devices, including monitors and cameras, big-screen image magnification projectors, audio, VCPs (virtual channel processors), scan converters, document cameras, digital whiteboards, and more.

Basic Rate Interface (BRI): The basic ISDN (see below) configuration, with two 64 kilobyte voice/data circuits, and one call-control circuit (for things like caller ID, call waiting, and so on).

Codec: Short for coder/decoder, the same way modem is short for modulator/demodulator. This is where the miracle occurs. It takes the analog signals from the camera and microphone, and codes them into zeroes and ones for transmission on digital telephone circuits.

End, Far: The place(s) at the other end of the dial-up line from where you are.

End, Near: Your end of the dial-up line.

Imux: Short for Inverse Multiplexor. Takes several channels of ISDN (see below) lines and makes them look like one big circuit to the codec.

IP: As in TCP/IP, the lingua franca of the Internet. Almost every computer made can speak IP, or Internet Protocol. Videoconferencing over IP works, and surprisingly well, over a private network. Out there in the Wild West of the public Internet, though? Anything can happen to your data before it gets to the other end--if it gets there. IP is an example of a packet-switched network (versus circuit-switched; see T1, below). Data gets broken up into bite-sized packets that get shot out over the Internet, with the hope that they arrive in time for re-assembly at the other end. Very cost-effective, but the routing devices to assign priority to time-sensitive packets (like voice and video) are not really in the market yet.

ISDN: Integrated Services Digital Network (some suggest it means It Still Does Nothing). Refers to digital telephone lines that make very efficient use of wires and bandwidth. Usually two channels of either 56 or 64 kilobytes capacity per Basic Rate Interface (BRI) circuit.

Kilobytes, 128: Two channels from a single BRI. Acceptable quality for a brief videoconferencing session with not a lot of activity, but not a satisfying experience for your events.

Kilobytes, 384: 384 kilobytes per second over six channels of ISDN service. You can get six channels from three BRI lines (see also ISDN), or by peeling six channels off a T1 (see below). Six channels, at 64k each, add up to 384k. This yields a very satisfying experience at nearly full-motion, but not recommended for basketball games.

Kilobytes, Switched 56: A single digital channel passing data at 56 kilobytes per second. OK for some desktop applications, but keep your expectations low.

PTZ Camera: PTZ means Pan/Tilt/Zoom. Refers to a motorized camera you can control with an infra-red remote. Steer it around, zoom in, zoom out, make sure you didn't put anyone to sleep at the far-end. Most systems allow you to control the far- and near-end's PTZ camera.

Scan Converter:Don't video without one. You need it to show presentations from PowerPoint or similar pro- grams over video. Converts the computer's VGA (video graphics array, the PC graphics display standard) output to the NTSC (National Television Standards Committee) standard on the backplane.

T1: Short for 1.5 megabytes per second, a T1 is a single digital circuit that can support 24 simultaneous channels of voice and/or data traffic. A big, fat pipe that only uses four wires. Some videoconferencing systems can use a full T1, but you will find that the quality does not exceed that of current systems running at 384k, at a much lower communications cost. T1 and 384k service usually refer to circuit-switched communications, where an end-to-end link is maintained for the duration of the call. Think of it as a railroad track from New York to Los Angeles with only your train on it.