Back in the day … You typically had a PABX and voicemail. If you were lucky someone may have paid extra for audioconference ability. There were capacity constraints on how many conferences could be held at one time and how many people could join in. If you did not have audioconferencing on your PABX, well there were 3rd party providers – Telecom (Spark) being the most popular, but they were not the only one.Video conferencing was for those with very deep pockets.IP networking and UC (Unified Communications) have radically changed the landscape. let’s see how.