Context: It was only in the 1980s that digital telephony transmission networks became possible, such as with ISDN networks, assuring a minimum bit rate (usually 128 kilobits/s) for compressed video and audio transmission. During this time, there was also research into other forms of digital video and audio communication. Many of these technologies, such as the Media space, are not as widely used today as videoconferencing but were still an important area of research. The first dedicated systems started to appear in the market as ISDN networks were expanding throughout the world. One of the first commercial videoconferencing systems sold to companies came from PictureTel Corp., which had an Initial Public Offering in November, 1984.

Question: In what decade was digital telephony transmission made possible?
Answer: the 1980s

Question: What is the minimum bit rate for compressed video and audio transmission?
Answer: 128 kilobits/s

Question: What is an example of an early form of digital video and audio communication?
Answer: the Media space

Question: In what form did the first dedicated videoconferencing system appear as?
Answer: ISDN networks

Question: What company offered the first commercial videoconferencing system?
Answer: PictureTel Corp.

Question: When did video and audio transmission come into being?
Answer: Unanswerable

Question: In November, 1984, what else was being researched?
Answer: Unanswerable

Question: What other minimum bit rate is not as widely used as videoconferencing?
Answer: Unanswerable

Question: What started to appear as the Media space was expanding world wide?
Answer: Unanswerable

Question: Where did the first compressed video transmission that was sold sold come from?
Answer: Unanswerable