Teleconferencing is having a meeting when the people are not in the same room. They are in different offices, different cities, sometimes different countries, and they join the meeting through the phone or through video on a computer. The word covers both kinds — a plain voice call with six people on the line is teleconferencing, and so is a video meeting where everyone can see everyone's face. Some people use 'teleconference' for voice only and 'video conference' when there are pictures, but this line is not firm and many speakers do not keep it. Notice the shape of the word: 'teleconferencing' with -ing is the activity or the practice in general, the way 'shopping' is. You say 'the company uses teleconferencing to save money on flights.' The single event is 'a teleconference' — 'we have a teleconference at three.' There is also a verb, 'to teleconference', but honestly people rarely say it; they say 'we'll do it by phone' or 'let's get on a call.' This word feels formal and a little office-ish, and also a little old now. It was the impressive business word of the 1980s and 1990s, when joining a meeting from far away was still special. Today, when almost every meeting is like this, people just say 'a call', 'a Zoom', 'an online meeting', or 'a meeting'. You will still meet 'teleconferencing' in company reports, IT documents, job descriptions, and hospital or government papers — places where writing is careful and formal. If you say it at lunch with friends, it sounds like you are reading from a manual.

遠距會議／視訊會議（電話會議）。台灣公司日常其實直接說「開線上會議」「開視訊」，或直接講「開 Zoom」；「電話會議」偏純語音那種。