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 systems as the "Broadcast Teletext Specification". With some tweaks to allow for alternative national character sets, and adaptations to the NTSC 525-line system as necessary, this was then promoted internationally as "World System Teletext". It was accepted by CCIR in 1986 as "CCIR Teletext System B", one of four recognised standards for teletext worldwide. In France, where the SECAM standard is used in television broadcasting, a teletext system was developed in the late 1970s under the name "Antiope". It had a higher data rate and was capable of dynamic page sizes, allowing more sophisticated graphics. It was phased out in favour