Re: Backward Compatibility Re: 202401100645.AYC Re: IPv4 address block

[Danny Messano via NANOG <nanog () nanog org>]

Yes, some folks made Bell very umm... blue at times.

Indeed I remember a Touch Tone fee on our bills until the 90's.  In fact, at one point I couldn't believe it was still 
a charge, as rotary phones had largely been replaced either as a choice or through attrition.

Consumers WANTED Touch Tone.  There didn't NEED to be a "strategy" to eliminate pulse dialing, as it cost the Baby 
Bells nothing to support it.  After deregulation the appearance of 3rd party devices with a DTMF pad and a pule/tone 
switch wasn't to help customers work around this "scheme" of AT&T.  The 3rd parties, in general, wanted to produce 
inexpensive sets that featured a pulse option for those people/areas stuck in the past.  You couldn't do that 
inexpensively trying to replicate the clunky rotary dial, and again, no one/few WANTed them.

I get the whole desire to promote EzIP as the greatest thing since NAT itself, but fabricating a bizarre hot take on 
the implementation of Touch Tone/DTMF as an attempted parallel to IPv6 vs IPv4 is kinda "out there".  The *corrected* 
history of Jay's actual does draw parallels, but more as a tale of how some people will do anything to save $1 (a 
month) even if the tech is highly beneficial.


Danny Messano
On Jan 15, 2024 at 14:12 -0500, Jay Hennigan <jay () west net>, wrote:
> On 1/15/24 09:37, Abraham Y. Chen wrote:
>
> > 2)    Allow me to share with you an almost parallel event in the PSTN,
> > to illustrate how tough is to achieve the replacement of a working
> > service, even under an environment with very strict backward
> > compatibility disicpline:
> >
> >     A.    The Decadic (rotary) Dialing (DD) technique worked well on
> > the telephone loop to a certain limit of distance for many years that
> > enabled the automatic telephone switching systems. But, it could not go
> > beyond the CO (Central Office).
> >
> >     B.    So, Bell Labs studied the use of DTMF (Dual Tone
> > Multi-Frequency) or commonly known as Touch-Tone as trademarked in US,
> > etc. The work started in mid 1940s.
>
> Actually, Bell had a multifrequency interoffice signaling system long
> before Touch-Tone was introduced to the public. Many of us old-timers
> were *very* familiar with this, much to the discontent of the Bell System.
>
> >     F.    Initially, AT&T offered the DTMF service for free (well,
> > covered by the rental of the new phone) to encourage that adoption.
> > Then, they raised the monthly service rate for lines still requiring DD
> > receiver hoping to gracefully forcing the subscribes to wean from using
> > DD phones.
>
> In the early days of deployment, DTMF was not free. It was typically $1
> more per month. IIRC, there was at one time an upcharge for 12-button
> vs. 10-button Touch-Tone pads. I have never seen a tariff with an
> upcharge for pulse dialing.
>
> >     G.    Guess what, the inertia of the huge DD phones out there in
> > the field accumulated through near one century made the strategy
> > impossible. That is, many subscribers would rather to pay one extra
> > dollar or so a month to enjoy having the old DD phone around, either to
> > avoid paying a new DTMF phone or just for the antique look of the DD
> > phone. This also created a nightmare of three types (DD, DTMF and
> > combined) line cards in the CO.
>
> With step-by-step, XY, or panel offices the DTMF receiver was an add-on
> that buffered the digits and outpulsed them at rotary dial speed. Pulse
> dialing always worked. Crossbar was also an add-on but with a crossbar
> marker the delay of converting to pulse was avoided. By the time ESS
> came around both pulse and DTMF were built in.
>
> Again, when and where was there ever an upcharge for pulse dialing?
>
> >     H.    As this went on, a version of phone with DTMF dial pad but
> > sending out DD pulses appeared on the open market (thanks to the
> > deregulation / break up the Bell System). Such novelty phones really
> > gave phone companies a hard time about the transition plan.
>
> The purpose of these phones was actually the opposite. It allowed a
> "modern" keypad-equipped phone to function on older lines not equipped
> with a Touch-Tone receiver. In GTE territory with Strowger switching,
> the digits from DTMF phones were buffered in the CO and outpulsed as
> rotary dialing. Bang out the number with Touch-Tone and you could hear
> the tick-tick of the digits being sent while you waited.
>
> These days people get upset with post-dial delay of more than a couple
> of seconds. It used to be substantially more, especially with
> interoffice calls.
>
> >     I.    In the meantime, IC technology advanced to have single chip
> > capable of both dialing techniques (even further integrated other
> > traditional line card functions onto the same chip) making the
> > transition plan moot.
>
> TTBOMK, every common BORSCHT chip accepts both.
>
> >     J    Nowadays, almost every line card type chip handles DTMF as
> > advertised. But, if you try a DD phone on it, chances are, it works anyway!
>
> Yes, because TTBOMK, telco central offices have always accepted pulse
> dialing and still do. SIP ATAs, on the other hand, mostly don't, with
> the exception of some older Grandstream units.
>
> --
> Jay Hennigan - jay () west net
> Network Engineering - CCIE #7880
> 503 897-8550 - WB6RDV