[comp.dcom.telecom] Payphone Innards

gmw1@cunixd.cc.columbia.edu (Gabe M Wiener) (09/23/89)

It's really surprising how talkative a telco man can become.  I've found an
easy way to strike up a conversation with a NYTEL repairman.  Just ask,
"Is the strike over?"  (knowing full well, of course, that is isn't).

Earlier today, I was passing a NYTEL guy finishing up work on a payphone and
I did just that.  He immediately started explaining that he was an upper-level
computer-systems manager filling in on the field work, in particular, in
replacing payphones.  "Replacing them?" so I asked.  "We're replacing the
electromechanical payphones with all electronic ones."  Gently pushing for
more info, I got him to open one up and show me the difference.

 From the outside they look identical to a regular telco slot.  But the
inside is radically different.  The upper section (the removable one) is
virtually hollow.  Nothing at all in there except for the inital coin
recepticle (but NOT the counter) the keypad, and a few other parts.  On the
inside section, however, are a number of removable modules.  The mechanical
coin detector/counter has been completely replaced with a digital one.  It
is a square-ish black module that is removable (he removed it to show it to
me) and connects to the chassis with a ribbon cable).  It's solid plastic on
the outside, and simply has a coin inlet and a coin outlet.

The only real electromechanical part left in there is the coin hopper, which
looked the same as always.  One thing I noticed on the inside of the phone
was an LCD readout.  I asked him about it, and he explained that it was used
in troubleshooting the phones.  Whenever these phones have problems (jammed
coins, etc.), they automatically call into a central computer and report it.
They also call in and report when the coin box is nearing full.  When a
serviceman comes to repair it, he plugs a special cord circuit into a
socket in the phone, and the LCD indicates various status factors of the
unit.  He explained that they also have time-clocks in them, so that they
will upload their statistical usage data during the night).

Another cute feature is that if the phone knows it has service trouble, it
will open up the coin hopper so that any coin put in will be immediately
returned.  If someone phones in trouble, the central computer can signal
the slot to open the hopper.

The actual coin signalling, however, is the same as usual.  Regular in-band
tones generated by an on-board module (he pointed it out.  It's on the upper
right side of the phone, right above the data-communications module).

All these modules, btw, plug in with ribbon connectors to the chassis which,
I assume, contains the motherboard.

There are only about 100 of these nifty phones in operation right now, but
they're trying to replace more and more of them as time goes on.  It's moving
rather slowly because of the strike.

So, gentle reader, we see that the strike DOES have some benefits...namely
running into service folks who will gladly take a payphone apart in front
of you to show you how it works.  On top of that, he also told me some
other interesting info, about my local switch, etc.

It seems that most telco folks will be glad to take the time to talk to
passers-by if they seem interested (this is especially true for the
management personnel who are filling in for the strike).


Gabe Wiener - Columbia Univ.      "This 'telephone' has too many shortcomings
gmw1@cunxid.cc.columbia.edu        to be seriously considered as a means of
gmw1@cunixc (bitnet)               communication. The device is inherently of
72355.1226@compuserve.com          no value to us."
WUI:650-117-9118          	       - Western Union internal memo, 1877