Prestel - Public Take-up of The Service

Public Take-up of The Service

While teletext services were provided free of charge, and were encoded as part of the regular television transmissions, Prestel data were transmitted via telephone lines to a set-top box terminal, computer, or dedicated terminal. While this enabled interactive services and a crude form of e-mail to be provided, gaining access to Prestel also involved purchasing a suitable terminal, and arranging with a Post Office engineer for the installation of a connection point known as a Jack 96A. In the 1980s, most domestic telephone installations were hard wired, so additional equipment such as a modem or Prestel terminal could not be connected to the telephone line without provision of a special socket.

Thereafter it was necessary to pay both a monthly subscription and the cost of local telephone calls. On top of this, some services (notably parts of Micronet 800) sold content on a paid-for basis. Each Prestel screen carried a price in pence in the top right-hand corner. Single screens could cost up to 99p.

The original idea was to persuade consumers to buy a modified television set with an inbuilt modem and a keypad remote control in order to access the service, but no more than a handful of models were ever marketed and they were prohibitively expensive. Set-top boxes were pioneered by the Nottingham Building Society for its customers, who could make financial transactions via Prestel.

The access situation improved as home computers became more commonplace, and by the late 1980s it was possible to use a machine such as a BBC Micro or Atari computer, equipped with a 1200/75 baud modem and some simple software, to access the Prestel service. Even the more gaming-orientated Sinclair ZX Spectrum had a large number of users via a low-cost modem called the VTX-5000. It was possible to buy downloadable content such as simple games. This would be encoded in a series of pages that were not human-readable, but encoded in blocks of rather less than 1 kilobyte per page. The header and footer of these pages was normal, however, so users could watch the pages appearing one after another to build up the downloaded file. To charge for content, generally the final pages of the downloaded file were charged at up to 99p each, the maximum possible page price on Prestel. By charging at the end of the download, problems with aborted downloads being charged for were generally avoided.

Because the communication over telephone lines did not use any kind of error correction protocol, it was prone to interference from line noise which would result in garbled text. This was particularly problematic with early home modems which used acoustic couplers, because most home phones were hard-wired to the wall at that time.

However, it was still an expensive proposition, and as a result, Prestel only ever gained a limited market penetration among private consumers, achieving a total of just 90,000 subscribers, with the largest user groups being Micronet 800 with 20,000 users and Prestel Travel with 6,500 subscribers.

The costs for businesses interested in publishing on Prestel were also expensive. This ensured that only the largest or most forward thinking companies were interested in the service.

The BT Prestel software development team developed a number of national variants of Prestel, all of which ran on GEC Computers. They were sold to the PTTs of other countries, including Australia, Austria, Belgium, Italy, Hungary, Hong Kong, Germany, Netherlands, New Zealand, Singapore, Yugoslavia, . Italy was the largest system with 180,000 subscribers. The Singapore system had a notable technology difference in that pages were not returned over the modem connection, but were returned using teletext methods over one of four TV channels reserved specially for the purpose, which had all scan lines encoded in teletext format. This higher bandwidth enabled use of a feature called Picture Prestel which was used to carry significantly higher resolution pictures than were available on other Prestel systems.

In 1990, BT introduced a new commercial model which effectively killed the domestic usage of the service, charging per-minute charges for access on top of the user's existing phone bill. Finally in 1991 it was decided that BT should move away from providing Value Added Services and should focus on network provision. Consequently the various consumer and business services were run down or sold off with such services as Prestel Travel and BTIS (BT Insurance Service) becoming private network services for third-party providers.

The 1984 hacker intrusion into the (very likely unused) Prestel mailbox of the Duke of Edinburgh garnered the network some unfavourable press, particularly when the simplicity of its security measures became apparent. The subsequent failure to successfully prosecute the intruders contributed to the introduction of the Computer Misuse Act 1990.

The Prestel name and equipment was eventually sold by British Telecom, and purchased by a private company, Financial Express, in 1994 and renamed New Prestel. During this period, the platform software was redeveloped onto a SCO Unix and Linux x86 platform away from the GEC 4000 Mini Computers. Additionally, the Citiservice financial data product was successfully redeveloped in house after being outsourced to Datastream during the time with BT.

Prestel Online, which was an Internet service provider spinoff, was sold to Scottish Telecom, and as of 5 June 2002, has since been merged into their other ISP activities.

The dial-up viewdata service was run down as the Internet gained in popularity.