kremen@AEROSPACE.ARPA (12/12/85)
My first question relates to a problem I am having with my telephone. I
am able to make local and long-distance calls fine. When I call, I can
hear the touch tones in the receiver. But as soon as my call is
connected, any touch tones I press are muted. I just hear a "click."
This makes it impossible to use my electronic banking or any other
services that use the tones as commands. For example, I am unable to
send voice mail to people at work.
So I called GTE repair. Of course the office personnel had no idea what
I was talking about. They said if what I told them was true, I would be
unable to make any local or long distance call. But after talking to a
supervisor's supervisor, I was finally able to get a repair-person to
come out in person.
So the repairperson came out. He was unable to find anything wrong. He
thought - as I did - that it was a central office problem. But what
stumped both of use was that his test set phone generated tones after
calls were connected. So he called a phone guru friend. After some
misunderstanding this guru said my phone had the wrong polarization.
Now my phone worked both back in Illinois and at another GTE site. He
explained, although I already knew this, that the other sites were
electronically switch and my new site was still step switched. He said
when a call was connected in most cases, the polarity of the line
reverses. According to this guru, my phone is an ATT Touch Tone and is
unable to switch polarities on step central offices. He indicated two
choices: buy a polarity suppressor (what is this?) at around $70.00 or
get a new phone.
My first question is can I make a polarity suppressor myself? What about
a double-throw double-pole switch that I flip after I get connected. It
would be hooked up to the red and green wires on the phone. Would this
work? Or should I buy a new phone? And if I buy a new phone, what should
I look for to be sure it can handle polarity correctly?
My second question concerns my last posting which was several months
ago. I asked about the S.I.T. (Special Information Tones) that are heard
when we either call a number that is not in service or our call cannot
go through. I never did receive the definite answer what was the purpose
of the tones, but someone sent a frequency listing of the tones to me.
Alas, I lost the name of who sent the list to me. So I was wondering if
you know anything about this to send me a copy of where they obtained
the frequency list (I have the frequencies themselves). I think the
reference was some AT&T Bell Labs Technical Journal article.
My third question is where I can get one of the phones (test sets) that
phone company repair people have? I am sure these can be bought, but
where? I think it would be a cool replacement to my phone with the "bad"
polarity." I would like a place in Southern California but any sources
will be extremely welcome.
If you can answer any of these questions, I would be in your debt. Send you replies to:
ARPA: kremen@aerospace
UUCP: {sdcrdcf, randvax, trwrb} ! aero ! kremen
BITNET: kremen%aerospace.ARPA@WISCVM.BITNET
Others: throught correct gateway to ARPA or UUCP telecom@ucbvax.UUCP (12/22/85)
In article <8512121712.AA25461@aero.ARPA> kremen@aerospace writes: >My first question relates to a problem I am having with my telephone. I >am able to make local and long-distance calls fine. When I call, I can >hear the touch tones in the receiver. But as soon as my call is >connected, any touch tones I press are muted. I just hear a "click." >...when a call was connected in most cases, the polarity of the line >reverses. According to this guru, my phone is an ATT Touch Tone and is >unable to switch polarities on step central offices. He indicated two >choices: buy a polarity suppressor at around $70.00 or get a new phone. >My first question is can I make a polarity suppressor myself? >ARPA: kremen@aerospace The transistor (or IC) circuitry in every phone needs DC of the right polarity to function. Older ATT phones "ensure" the right polarity by having a single diode in series with the electronics and wiring the telephone office and your telephone jack to a consistent polarity. Most other telephones use a rectifier bridge to make them polarity independent. When ATT originally did this, they probably saved $3 per phone ($1 per diode), but now diodes are a nickel each. It's certainly possible to modify the network, but it's too hard to perscribe details. The general idea is: Old: |-------------| --| tone circuit|--->|--- +|-------------|- New: --|---------------|------ |AC Bridge AC| | + - | |---------------| | | +| -| |--------------| | tone circuit | |--------------| There are a couple of possible locations for the bridge: the easiest to find may actually be between the hook switch and the entire non-bell circuitry rather than isolated to tone circuit. -- Darrel J. Van Buer, PhD System Development Corp. 2525 Colorado Ave Santa Monica, CA 90406 (213)820-4111 x5449 ...{allegra,burdvax,cbosgd,hplabs,ihnp4,orstcs,sdcsvax,ucla-cs,akgua} !sdcrdcf!darrelj VANBUER@USC-ECL.ARPA