DREUBEN@eagle.wesleyan.edu) (DOUGLAS SCOTT REUBEN) (07/27/90)
In regard to the recent discussion about creating an "infinity
transmitter" for cell phones:
I have an Audivox CMT-450, and when I want to make it transportable, I
have to place it in an awkward carrying case, with lots of cable, and
then add an antenna lead that bleeds the RF of the cell phone so badly
that even when the handset is removed from the main unit (and hence
the speakerphone in the cradle is "off"), you can hear the
conversation just as clearly, and even more loudly, through the
speakerphone. You can also hear the call through any nearby FM radio,
or I've noticed that it slightly alters a TV signal as well. Note,
this only occurs in the portable unit, not while it is installed
properly in the car. (I don't have Audiovox's designated unit [which
costs more then the phone], but some cheap, generic one that is really
a piece of plastic, a rechargable battery, a few wires, and a cloth
carrying case.)
Anyhow, when a call comes in, I can hear the phone click and send
signals (high pitched tones, it seems) back and forth, and if there is
any static I can hear that too. So, I can generally tell if someone is
calling WAY before that phone starts ringing. What's more interesting,
when I switch from one service area to another (like along I-80
between San Francisco and Sac), you can hear the phone drop the old
system, and "communicate" with the new system that it is in the new
system's area. (Or at least it makes some clicks and you can hear some
signals when the ROAM light goes on or off.) (Every time it
establishes itself in a new system it also sets my radar detector off,
which a real pain on roads that straddle two service areas, and thus
tend to go back and forth between systems!)
What this all has to do with listening in before someone presses the
"SEND" button is that I gave the phone to my brother to use while
driving around in San Francisco. I called him at about 5:30PM, and he
was in a bad area and/or all the "good"/clear channels were being used
in his site, so there was a really bad connection. The weird thing was
that I HEARD the static BEFORE the call even started ringing, and
during the ringing the static went in and out, as if the ringing were
being sent from the cell phone, over the air, to the cell tower. From
what I understand, it is the MTSO or some central device which creates
the ring signal, so why did I hear static mixed along with the signal?
It seems as if some channel were being opened to the cell phone (hence
the static which I heard from the land line phone I was calling from),
while at the same time ringing was being generated from the central
switch and was being intermixed with the "signal" from the cell phone
my brother had in his car.
Again, I'm not sure, but it SOUNDS to me like I was getting some sort
of signal from my phone, (and not just progress signals generated at
the switch), which leads me to think that although maybe I can't hear
the actual sounds in the car becuase the handset/speakerphone isn't
activated, I am getting a real signal from the phone itself. Note that
in most other instances when I called the car in good-reception areas,
I heard nothing until the call was actually answered.
This happened on both GTE Mobilnet and Cell One (I ROAM with Cell One
and have HOME service with GTE ... long story) so I doubt it's
specific to just one company or the specific location my brother was
in.
Oh, and I also managed to get my hands on the complete set of
parameters for programming an Audioxov CMT-400 series phone. (I think
500's as well ... or is it 5000?) Basically, its a list that tells you
what each of the registers are used for and how to program your phone.
If anyone is interested, I'll type it up and send it along for posting
on the Digest.
P.S. to John Higdon: YES, GTE in LA *IS* worse ... Lesse: I've lost
maybe $10 worth of coins in their payphones in LA and Palm Springs and
then the phone went dead. I've gotten the INWARD Operator by making
calling card calls to New York City, I've killed the phone (made the
line go dead) by making local calling card calls, I've gotten
call-waits while I'm on a 0+ call and couldn't drop the party that
call-waited me without hanging up the whole call, and, GTE LA *JUST*
got call-waiting in most of their exchanges in 1985, or so they
announced in a full-page ad I clipped from the {LA Times} ... wow!
What progress!.
In comparison, GTE in the Bay Area seems like a real company compared
to what I had to put up with in LA a few years ago ... (But since you
deal with them a lot more often than I probably do, I'll take your
word as to how bad they are.) Oh, and there are LOTS of GTE
payphones along CA-17 near Los Gatos, all which never stole my money
and connected my calling card calls correctly (as to the bill,
well, we'll know in a month! :-) )
Doug
dreuben@eagle.wesleyan.edu
dreuben@wesleyan.bitnet
[Moderator's Note: Yes, please send along the CMT-400 information. PT]