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502-542-406 i1 Oct70 - 568HT 1568HT Service

October 1970, issue 1.  568HT is an early touch tone set with 22-type dial including red P (Priority) and SG (Special Grade) buttons and round line keys. For 2- and 4-wire service. SG connected to a 4-wire line if available. Replaced by the 1568HT, which had square line keys. Early dials had a different button contour than the 25-type dials used on the 1500-series production sets. 568HB has a rotary dial. Includes info formerly in 502-532-100, 502-532-400 and 502-532-430.  Contributed by Rick Walsh.

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