Minitel and Videotex
instant messaging or downloading large datasets, as large pieces of data would have to be broadcast to every single user, making the entire broadcast prohibitively slow. Teletext often operated on unused TV frequencies or between frames in normal programmes. The technology to receive Teletext was widely available in TVs from the 80s right up until the digital transition, after which it was replaced by more sophisticated standards, although they still use the same concept of downloading all pages while displaying only the required ones. Videotex protocols, on the other hand, used two-way communications, meaning pages can be generated on demand. Thanks to this, Videotex terminals are able to display dynamically rendered pages and can be interactive. For example, the ‘ pink messenger ’ ULLA, operated on Teletel, had two million monthly connections at its peak (Charnay, 2012). Teletel, the Videotex system at the heart of Minitel, operated over mobile phone lines, allowing easy adoption for people who already had telephone lines, and later, encouraging and easing the expansion of landlines. The modem was packet switched but always connected to the same central directory service (PAVI). In theory, you could use any central directory you wanted, rendering the service decentralized. However, in practice, the only large Teletel networks (PAVIs) were 3615 (the main network operated by France Telecom) and 3617 (their premium offering) (MCbx, n.d.). Both PAVIs were billed by time spent connected to the telephone line. However, these two numbers were only intermediaries. After connecting to one of the networks, you could enter a ‘ code ’ , which would redirect you to the service registered under that code. The central service operated by France Telecom took care of billing, making the offering more attractive to potential businesses that would operate on Teletel. However, this came at a price. France Telecom operated a purchase system, by which service providers could bill the user for products or services consumed inside Teletel. Similar to modern app stores, a hefty cut was taken by the middleman, in this case France Telecom rather than Apple or Google. However, by using a middleman, the user had their identity kept private from the service providers, and their billing went entirely through France Telecom, increasing trust (Driscoll, 2017). The pages available on Teletel were tightly regulated for privacy. Another similarity between the two is the distribution model. On both Android and iOS devices, it is technically possible to install apps from outside the official app store. However, this is discouraged and rarely happens in day-to-day usage. Likewise on the Minitel, it was possible to dial a different number, but most services were only on the official 3615 or 3617 PAVIs. Furthermore, the data used for modern mobile network connections is usually billed monthly, just like the monthly flat fee used for most X.25 networks (International Telecommunications Union, 1991), another similarity between the two systems. X.25 used a virtual circuit architecture (Schwartz, 2010). This combination of packet and circuit switching allowed for very high efficiency long-term connections to take place. Initializing a connection took a while, but once initialized, data could be sent faster than packet-switched networks. The only disadvantage to this approach compared to packet-switching was that the initial connection took a while. However, this did not pose a problem with Teletel, since all connections were made via a PAVI. This virtual circuit switching was essentially a form of compression, allowing packet switching to take place without the need to attach expensive addresses to each of the relatively short packets. X.25 even supported 60-bit addresses. Compared to IPv4, which has 32-bit addresses, this is huge, especially for the time. Furthermore, each
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