<P> The code / speed conversion between "3 - row" Baudot and "4 - row" ASCII TWX service was accomplished using a special Bell "10A / B board" via a live operator . A TWX customer would place a call to the 10A / B board operator for Baudot--ASCII calls, ASCII--Baudot calls and also TWX Conference calls . The code / speed conversion was done by a Western Electric unit that provided this capability . There were multiple code / speed conversion units at each operator position . </P> <P> AT&T published the trade magazine TWX, related to the Teletypewriter Exchange Service from 1944 to 1952 . It published articles that touched upon many aspects of the technology . </P> <P> Western Union purchased the TWX system from AT&T in January 1969 . The TWX system and the special US area codes (510, 710, 810 and 910) continued until 1981, when Western Union completed the conversion to the Western Union Telex II system . Any remaining "3 - row" Baudot customers were converted to Western Union Telex service during the period 1979 to 1981 . Bell Canada retained area code 610 until 1992; its remaining numbers were moved to non-geographic area code 600 . </P> <P> The modem for this service was the Bell 101 dataset, which is the direct ancestor of the Bell 103 modem that launched computer time - sharing . The 101 was revolutionary because it ran on ordinary unconditioned telephone subscriber lines, allowing the Bell System to run TWX along with POTS on a single public switched telephone network . </P>

Advantages and disadvantages of telex in business communication