10 forgotten wonders of 1980s homes

Jacob Ritorto jacob.ritorto at gmail.com
Wed Dec 30 00:25:29 CST 2015

On Wed, Dec 30, 2015 at 12:30 AM, Christian Gauger-Cosgrove <
captainkirk359 at gmail.com> wrote:

> On a Number 5 Crossbar, your DTMF was never converted to dial pulse
> for the switch itself. The Touch-Tone Register would connect to a
> digit translator that inputs the 2-of-5 binary code directly into the
> relays of the Originating Register (which can still receive dial
> pulse). On Number 1 Crossbar and Panel however your DTMF would be
> converted to 20 pulse per second dial pulsing. Only in Step-by-Step is
> your DTMF converted down to "normal" 10 pulse per second dial pulsing;
> though it should be noted that in step it either gets converted by a
> "dumb" Touch-Tone Reciever Converter (DTMF goes in, dial pulse goes
> out) in a direct control step, in a common control step (yes that was
> a thing) the DTMF actually ends up getting converted in the same way
> as on #5XB with the common control elements dial pulsing.
> However it should be noted: Crossbar switches make noise when
> connecting through the switch fabric; and depending on trunking and
> the kind of switch you're calling you might hear dial pulsing, panel
> call indicator pulsing, or revertive pulsing. RP would be sent on a
> direct connection between a crossbar to a Number 1 Crossbar or Panel
> switch (and to Number 5 Crossbar occasionally). PCI is something you'd
> *never* hear in the 80s, since the only tandems that required PCI
> (namely Panel Sender Tandem) were gone by the 70s, and the tandems
> that replaced them (Crossbar Tandem) while it can still "speak" PCI
> would be more likely to use MF tones; also end offices that would use
> PCI, namely manual offices, were also dead and gone by the 80s. Dial
> pulsing however... well that goes to step offices, and if you have a
> step tandem anywhere in the chain (you could have a #5XB to #5XB call
> which you'd think would be MF'd; but if you have a step tandem you get
> dial pulse).

okay, this is _really interesting_.  Where can I read more?

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