Teletext systems expensive cost of NABTS decoders, costing in the thousands of dollars upon their release to the public. NABTS, however, was adopted for a short while by American TV networks NBC & CBS throughout the early-to-mid 80s, CBS using it for their short-lived ExtraVision teletext service, which premiered after the early Antiope & Ceefax trials by CBS & KNXT, and NBC, who had a NABTS-based service called NBC Teletext for a very short time in the mid-1980s. NBC discontinued their service in 1985 due to the cost of NABTS decoders not dropping to an affordable level for the consumer public. The
Teletext comparable to systems such as France's Minitel. The modem was asymmetric, with data sent at 75-bit/s, and received at 1200-bit/s. This two-way nature allowed pages to be served on request, in contrast to the TV-based systems' sequential rolling method. It also meant that a limited number of extra services were available such as booking event or train tickets and a limited amount of online banking. Teletext information is broadcast in the vertical blanking interval between image frames in a broadcast television signal, in numbered "pages." Teletext allows up to eight 'magazines' to be broadcast, identified by the first digit of