Touch-Tone<tm> on SxS

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.
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While not exactly the same thing, when Blackwell, Okla., was cut to dial with a new 5XB, it homed on Ponca City, a step office. It also had high usage trunks from the 4A in Oklahoma City. You could readily tell which route your call had taken, because if it used the high usage trunks from the 4A, the call setup was almost instantaneous, while if it took the final route through Ponca City, the 4A outpulsed to the step office in Ponca City and through it to Blackwell with step pulses. Wes Leatherock
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I admit it's kinda strange to think of a 5XB with a primary path via a SxS office. ;-)
On the former 712-366 office, some unusual timing was evident. In particular, calls to the Council Bluffs 1E office actually completed faster (712-322, et. al.) than those intra-office to 712-366. The calls to the 1E evidently used the first selector only with rapid MF outpulsing, while it took more time for the various selectors in the SxS office to complete the intra-office calls.
Many calls from 712-366 at the time went via the downtown (Omaha) xbar tandem. You could always hear the MF burst to the newer offices, the {scratch-scratch} to panel or 1XB, or the {click-click-click ...} to a step office.
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I don't know about the 5XB, but a 1 and 1AESS could do overlap DP to a step office, which cut the time down significantly, especially for a subscriber using a rotary dial.
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Sam Spade
The high usage group was always the primary path. The final group got the calls when all HU trunks were busy. That's why it was called the final group. Wes Leatherock
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