Videoconferencing has been possible since the 1960s, when AT&T developed the world's first videophone.
However, the expense and organisational hassles involved with the early technology meant it was seldom used, even by major US companies, until the late 1980s.
The establishment of the H.320 standard for ISDN in the early 1990s was a major advance in the usability of videoconferencing, as it set down the standard for the technology, so that equipment from different vendors would be compatible.
H.320 is an "umbrella standard," one that incorporates several other standards in the voice, video and audio areas.
Another advance was H.323, which did the same for IP, incorporating many of the same standards under the H.320 banner, but setting the standard for transmission by packet.
Another standard, H.324, allows for videoconferencing over the public telephone network (PSTN) via a modem.
H.324 may represent the future of videoconferencing but it remains to be seen whether the good old analogue PSTN is capable of handling H.324-based videophone applications which are beginning to be rolled out but aren't yet widely deployed.
One company, V-Span, has produced a gateway allowing communication between H.320 and H.324, in the same way gateways allow H.320-H.323 contact.
The key to videophoning via H.324 is having a 28Kbit/s modem; the H.324 standard will compress voice to 6Kbit/s, leaving the rest open for video.
According to www.324.com, a vendor-independent website dedicated to the standard, videophone products likely to appear in the next two years include stand-alone videophones, TV-bases videophones and PC-based vidoephones.
324.com notes videophones won't deliver "TV" quality.
And what of the more immediate future for H.320 and H.323 standards-based services?
IDC analyst Nicky Walton, in a report published in October, noted that if videoconferencing is offered over managed IP WAN or LAN connections, enough bandwidth can be assigned to the network to guarantee the quality of the connection.
"Therefore, it is possible to transmit high quality compressed video across an IP network which can be bundled into the fixed price of and IP circuit. In comparison, standalone ISDN-based videoconferencing units incur per minute charges."
And what of the impact of the September 11 terrorist attacks?
"There is no doubt there will be an increased emphasis on businesses having a number of dispersed locations, which, combined with restrictions on travel, will drive voice and video conferencing.
"While IDC believes such trends will help drive the take-up of IP-based services, the deployment of videoconferencing over IP still raises questions about the large amounts of bandwidth required and the cost of switching to an IP network.
"Proponents of IP networks and services claim companies will be able to regain a return on investment from an IP network in the immediate to middle term.
"This means these services are still limited to either large corporates or small to medium sized companies in a position to run the risk of a delayed return on investment."