Date: Tue, 19 Jun 90 21:04:49 PDT
From: "John R. Covert 20-Jun-1990 0007" <firstname.lastname@example.org>
Subject: AMR Meter Reading, No Test Trunks, and Call Forwarding
>The AMR System allows a utility to remotely acquire meter
>reading data from its customers using the existing telephone line to
>the customer premises. This wil be done by installing an Access
>Control Unit (ACU) in the local telephone central office which will be
>connected to the central office switch via a "no test trunk" unit.
"No test" afficionados will remember an interesting interaction
between "no test" and call forwarding, at least in No 1 and 1A ESS.
When a call is initiated to a number via a "no test" trunk, if the
line is call forwarded, the "no test" trunk will not seize the line;
reorder is returned. This was intended to tell operators doing busy
verification that busy verification can't currently return information
consistent with dialled calls due to call forwarding.
Of course, operators aren't typically familiar with this, and get
quite upset when they can't get onto a line via busy verification.
Years ago, when IDDD was first made available in Atlanta, some friends
and I spent a few evenings calling up operators and asking for the
codes for places like London, Paris, and smaller cities. The
operators weren't trained on this, and it would sometimes take quite a
bit of convincing to get them to call the overseas operator for the
This was _really_ early in the IDDD days; even rate and route didn't
have the info yet, and TSPS didn't yet support operator dialling --
all overseas was either direct dialled from No 1 ESS or placed by IOTC
operators. Of course, the overseas operators were properly trained,
and the local operators were often very upset that the overseas
operators would give us the information after the local operators had
just finished sternly telling us that we couldn't possibly dial the
calls ourselves and that the information we were asking for was
confidential telephone company info.
This made them curious, and since it was late at night, they weren't
very busy or well supervised, and verification wasn't scrambled in
those days. Soon we started noticing the tell-tale "ta-tic" of the no
test trunk seizing our lines. We'd talk to the operators; tell them
we knew they were there, flash for add-on, which would momentarily
yank them off the line and then bring them back on with dial tone,
then flash back to our call, and do all sorts of things that further
aroused their curiosity.
Then we told them "we're going to disable your verification trunks for
the next ten minutes while we have a private conversation." Back then
it was still possible to forward your calls to your own number. Doing
this left everything normal, except that the no test trunks couldn't
access your line. Then when we'd drop the call forwarding, we'd end
up with operators from several consoles all on our lines at once.
"Ta-tic, ta-tic, ta-tic." "Aha, we count three of you there now."
This further confused them, since they were mis-trained to believe
that no one could hear them when they first came on the line with
verification to listen. Great fun.
BTW, I assume that forwarding to self was disabled when someone with
message rate service got a phone bill after a month of paying message
units for each incoming call! There may have been fifteen units per
call, since the code in those days counted fifteen times through a
forwarding loop in the same central office and then stopped whereever
it was, which explains why two numbers in the same machine forwarded
to each other would "swap" numbers.
Now, of course, the impact of this on AMR is that if someone goes out
of town and uses call forwarding for a while around meter reading
time, it won't be possible for the no test trunk to get to the meter.