Teletext (or "broadcast teletext") is a television information retrieval service developed in the United Kingdom in the early 1970s. It offers a range of text-based information, typically including national, international and sporting news, weather and TV schedules. Subtitle (or closed captioning) information is also transmitted in the teletext signal, typically on page 888, 777, 333 or 150.
Read more about Teletext: Technology, Other Systems, Later Developments, Levels, Digital Teletext, Other Teletext-related Services, Cessation of Service