Ma Bell did have one rather innovate method of providing Touch-Tone on step offices, combined with other features.
Their 'directorized' SxS offices used a common control unit between the linefinder and the first selector. This provided dial tone and received digits, either dial pulse or Touch-Tone in real time and stored them. When dialing was complete, the common-control unit then either drove the switches to complete the intra-office call or selected a trunk to another office and outpulsed the appropriate digits using the method the far-end office spoke.
The office I remember best of this type was the Manawa office in Council Bluffs, Iowa, 712-366. This was cut to a DMS-10 ca. 1984. It had the precise dial tone of other TT-compatible offices, but an incredibly funky set of tones for the ringback and busy-back tones.
When rotary dialing, the register-sender (or whatever you call the common-control unit) did exhibit the classic 'clunk' between digits, typical of SxS offices.