What is this device called [Telecom]
Tom Horne
many years ago, that would isolate non standard telephone equipment from
the PSTN and still provide ringing and talk current to the non standard
equipment. Can anyone tell me whether such devices still exist and what
they are called?
--
Tom Horne
"This alternating current stuff is just a fad. It is much too dangerous
for general use." Thomas Alva Edison
***** Moderator's Note *****
There were a variety of interface devices that were made available
after the FCC mandated interconnection. I'm most familiar with the
CDH, which was intended to connect POTS lines to customer provided
equipment. It did the job, but it was too complicated: not only did it
have separate supervision leads that were isolated from the talk path,
but it had separate ringing leads as well. There might have been PBX's
or other CPE which could access the CDH directly, but ordinary key
equipment could not: to use it for CPE key equipment, you needed
_another_ interface to match the CDH interface.
Ma Bell had too many interfaces and they cost too much to install and
rent: it was inevitable that the FCC would dictate type-acceptance and
allow direct connections. I don't remember when that happended, but it's
been the norm ever since.
Sam Spade
> There used to be a device that could be obtained from AT&T, lo these
> many years ago, that would isolate non standard telephone equipment from
> the PSTN and still provide ringing and talk current to the non standard
> equipment. Can anyone tell me whether such devices still exist and what
> they are called?
I vaguely recall hearing of such a device. In California we were spared
that because the CPUC got out ahead of the FCC by establishing a
certified premise equipment program. Any equipment so certified could
be connected directly to the network provided it was "registered" with
the LEC.
Robert Bonomi
Tom Horne <hor...@verizon.net> wrote:
>There used to be a device that could be obtained from AT&T, lo these
>many years ago, that would isolate non standard telephone equipment from
>the PSTN and still provide ringing and talk current to the non standard
>equipment. Can anyone tell me whether such devices still exist and what
>they are called?
The _most_common_ such beast was a "DAA", required, pre-carterfone, for
connecting a customer-owned _modem_ to the phone line.
Such devices have, for all practical purposes, disappeared from the marketplace
after the FCC mandated a 'standard' isolation interface for CPE, with 'type
acceptance' methodology for approving manufacturers.
Type-accepted line isolation modules are available from practically any
significant component manufacturer for the telecom industry.
See, for example:
<http://www.nuhorizons.com/products/NewProducts/poq20/clare.html>
For _lots_ more, google for "telephone line interface IC".
Reed
> There used to be a device that could be obtained from AT&T, lo these
> many years ago, that would isolate non standard telephone equipment from
> the PSTN and still provide ringing and talk current to the non standard
> equipment. Can anyone tell me whether such devices still exist and what
> they are called?
For dialup modems, there was a device called a DAA (Data Access
Arrangement). There was a manual dial/answer version, and an
auto-answer version. No longer required since inception of Part 68
registration, and RJ jack types.
Tom Horne
>
> There were a variety of interface devices that were made available
> after the FCC mandated interconnection. I'm most familiar with the
> CDH, which was intended to connect POTS lines to customer provided
> equipment. It did the job, but it was too complicated: not only did it
> have separate supervision leads that were isolated from the talk path,
> but it had separate ringing leads as well. There might have been PBX's
> or other CPE which could access the CDH directly, but ordinary key
> equipment could not: to use it for CPE key equipment, you needed
> _another_ interface to match the CDH interface.
>
> Ma Bell had too many interfaces and they cost too much to install and
> rent: it was inevitable that the FCC would dictate type-acceptance and
> allow direct connections. I don't remember when that happended, but it's
> been the norm ever since.
Yes Bill, but that doesn't help with stuff that is not type accepted.
Isn't the new term of art certified? I'm trying to devise a way to
patch the PSTN incoming calls to manual switchboards that predate
customer dialing. If you connect the interconnect terminals of some
of those boards it will look like an off hook condition to the PSTN.
Bruce L.Bergman
<hor...@verizon.net> wrote:
>There used to be a device that could be obtained from AT&T, lo these
>many years ago, that would isolate non standard telephone equipment from
>the PSTN and still provide ringing and talk current to the non standard
>equipment. Can anyone tell me whether such devices still exist and what
>they are called?
Protective Connecting Arrangement or Voice Connecting Arrangement.
Popular varieties that went directly from a POTS line to the answering
equipment included Universal Service Ordering Codes RDL RDM RDMZR RDY.
Go look up BSP's under those codes. 463-340-101 covers the RDMZR,
463-340-110 and 463-340-111 cover the RDL and RDM There is an index
up at
http://www.telephonecollectors.org/DocumentLibrary/BSPs/463Division/463-000-000-Index.pdf
There may still be a pile lurking in a warehouse (Sandman?) but
since Carterfone (1968) and Type Acceptance nobody needs them.
>***** Moderator's Note *****
>
>There were a variety of interface devices that were made available
>after the FCC mandated interconnection. I'm most familiar with the
>CDH, which was intended to connect POTS lines to customer provided
>equipment. It did the job, but it was too complicated: not only did it
>have separate supervision leads that were isolated from the talk path,
>but it had separate ringing leads as well. There might have been PBX's
>or other CPE which could access the CDH directly, but ordinary key
>equipment could not: to use it for CPE key equipment, you needed
>_another_ interface to match the CDH interface.
>
>Ma Bell had too many interfaces and they cost too much to install and
>rent: it was inevitable that the FCC would dictate type-acceptance and
>allow direct connections. I don't remember when that happended, but it's
>been the norm ever since.
It would have been nice if they made Couplers that transparently
passed the line and ring voltages through, as if they weren't there. I
suspect the hidden strategy was to make CPE connections as difficult
and expensive as possible, so customers would give up and lease Telco
equipment for that nice recurring monthly charge.
The Couplers were a pain to get from the Telco because you had to
find a CSR who knew how to order them, and certain models were in
short supply toward the end. And expensive to lease for what they
were. But they eliminated the threat of immediate disconnection for
'attaching foreign equipment' to Ma Bell's lines.
And while they were a pain for POTS voice work, they actually made
building and running a Dial-A-Joke (Guilty...) or a movie theatre
"Today's Shows and Showtimes" line easier. The coupler gave you dry
closures for ring voltage and line supervision status, you gave the
coupler dry closures for off-hook and on-hook commands, fed it your
outgoing program audio at the right levels, and it did the rest.
You only needed a tape player or two as program source with a
half-watt or so speaker level output, a power supply, relays, pilot
lamps, switches and a call counter to build the machine.
--<< Bruce >>--
Robert Bonomi
If you'd said -that- in the first place, you'd have gotten better first-round
answers. <grin>
Anything 'off the shelf' in the (even semi-) modern world is going to require
quite a it of custom 'glue' logic to adapt that cordboard to the weirdness of
the CPE side of the adapter box. You may as well just get one of the (many)
registered, type-accepted, 'FCC part 68' qualified, 'phone line interface
integrated circuits (whew!!), and roll your required custom interfacing logic
around -that-. Such chips are only a few dollars (at most), quantity one.
Fred Atkinson, WB4AEJ
coupler for my home phone line for a phone patch for my ham radio
station. I was moving into a new place so I asked them to put it in
when they came.
The people in the ordering department were clueless on this (even
the supervisors). They kept telling me that this was against the
telephone company's tariffs and that they wouldn't install it. When I
insisted they were wrong, they just passed me to another, and yet
another, and yet another person who was equally clueless.
I told them that I was requiring them to install it. Then I got
passed to a supervisor who was the one who insisted that this was a
violation of the company's tariffs. The whole thing went on for days.
Suddenly I remembered that I had a very knowledgeable ham buddy
that worked in the telephone company's marketing department (Chad
Burriss, WB4REC, who passed away some years back). I told this
supervisor that I wanted her to call him and that he would explain the
whole thing to her. At that point she changed her tune. She told me
that she did not question what I said (the hell she hadn't) but that
they had to check it out. Name dropping seemed to work.
A couple of days later there I received a message saying that they
had resolved the issue and would proceed with the installation of my
QKT coupler when they came over to install my phones. When I called
in to finalize the details, I was once again asked what I wanted it
for.
I told her that I had already been through a knock down, drag out
fight with the business office over it. I told her that the business
office had already admitted they were wrong and agreed to put it in.
I asked her if we really had to go through that again.
She said, no (thankfully) and scheduled the installation.
They called me back and told me that they didn't have one in
stock. They said they would order it, install my phones for now, and
then send someone back over to install the coupler when it arrived.
They agreed not to charge me for the second installation visit. A few
weeks later, they showed up and installed the coupler on my phone.
I remember reading things where Bell was essentially complaining
about people illegally connecting equipment to their lines. I would
answer that people wouldn't do that if they didn't have to put up with
that kind of abuse when they called in to do it legally (fifty cents
per month was the rate for the coupler and I didn't have any problem
with paying that).
After type acceptance began, manufacturers started selling phone
patches that were type accepted and could be plugged directly into the
line. Additionally, there was a move to grandfather all previously
manufactured phone patches so they could be used on the PSTN without
an interconnection device.
One of the major problems of a totalitarian phone systems is going
through things like this. This is why I jumped for joy when the
telephone monopoly was broken up. Thank you Carterfone, Hushaphone,
MCI, and the rest.
I won't say that it solved all of the problems. But as with any
democracy, freedom carries individual responsibilities.
I just wish the current administration realized that.
Fred
***** Moderator's Note *****
There have been books written about the hidebound management at Ma
Bell, and about the arrogant and intractible attitudes exhibited by
many of her employees. I went through the same frustration you
experienced when I ordered an interface for a phone patch - and _I_
was working at New England Telephone!
It got done eventually. Elephants are not efficient because they're
nimble.
By the way, I hope you'll agree that one of the individual
responsibilities which accompanies our freedom is the obligation to
respect others' viewpoints, and to accept that not everyone will
agree with our own.
hanc...@bbs.cpcn.com
>
> There have been books written about the hidebound management at Ma
> Bell, and about the arrogant and intractible attitudes exhibited by
> many of her employees. I went through the same frustration you
> experienced when I ordered an interface for a phone patch - and _I_
> was working at New England Telephone!
I'm sorry Mr. Atkinson had trouble, but back then our experience was
totally the opposite. We obtained such devices for computer terminals
without any trouble. We abandoned the more expensive Bell-leased
Teletypes (the kind with the ORG button and built-in automatic modem)
for cheaper terminals and modems, and even though Bell would lose
revenue, they fully accomodated our needs.
To be fair, we must remember there are also books written about how
some pre-divesture customers and businesses tried to get a free ride
in blatant violation of the tarriffs in existent in those days, as
well as how the pre-divesture Bell System bent over backwards to
accomodate customer service needs.
In those days, the Bell System was forced to waste its money servicing
repair calls that were the result of bad customer owned equipment,
such as improperly wired bootleg extension sets or unauthorized
modifications to a business key system. Nobody talks about that side
of the issue. Contrary to myth, they did not disconnect the
subscriber's service or rein the wrath of the heavens upon the hapless
subscriber as critics complained, but merely disconnected the
offending device. Even when using their own personally-owned device,
customers still expected the Bell System to provide end-to-end
responsibility for calls (unlike today).
Good public policy does NOT result from anti-utility attitudes that
favor cream-skimming. In pre-divesture days people demanded both rock-
bottom rates AND super high levels of service. That is, they expected
actual-cost rates on busy corridors like Chicago to St. Louis, but
also expected cross-subsidized rates on light volume and expensive
corridors such as in the west.
Tom Horne
I'm afraid that customizing chip logic is beyond my skill set. I was
hoping, vainly it seems, that there existed some box that took in a loop
supervised phone line and a supply of some form of power and put out a
voice pair, dry closure on ring, and some means to signal the outside
lines supervision state.
Scott Dorsey
You are trying to do this today or you are trying to do this in 1970?
There are some old Data Access Arrangement boxes out there, but they are
not particularly useful today. Some of them have dialing hardware, some
of them do not. Most have four-wire interfaces but some have two. In
1970 they were VERY useful because they provided a political line of
demarcation.
If you have an existing switchboard, bringing telco lines into it as a
trunk shouldn't be a huge problem, depending on what kind of switchboard
it is. Even if it's for a common-battery phone, you should be able to
use a repeat coil to get DC isolation between the telco circuit and the
phone.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Scott Dorsey
>> ***** Moderator's Note *****
>>
>> There have been books written about the hidebound management at Ma
>> Bell, and about the arrogant and intractible attitudes exhibited by
>> many of her employees. I went through the same frustration you
>> experienced when I ordered an interface for a phone patch - and _I_
>> was working at New England Telephone!
>
>I'm sorry Mr. Atkinson had trouble, but back then our experience was
>totally the opposite. We obtained such devices for computer terminals
>without any trouble. We abandoned the more expensive Bell-leased
>Teletypes (the kind with the ORG button and built-in automatic modem)
>for cheaper terminals and modems, and even though Bell would lose
>revenue, they fully accomodated our needs.
That's because you knew the right person to call.
The same was the case for anything other than straight POTS... if you
knew the radio loop guy for the city, you'd make a call and get a loop
installed. If you didn't know the radio loop guy for the city, good
luck getting anyone in the business office to figure out what an 8KC
loop is or how to get you one.
Scott Dorsey
>
>I'm afraid that customizing chip logic is beyond my skill set. I was
>hoping, vainly it seems, that there existed some box that took in a loop
>supervised phone line and a supply of some form of power and put out a
>voice pair, dry closure on ring, and some means to signal the outside
>lines supervision state.
Sounds like a toggle switch and a repeat coil to me. What precisely are
you trying to do?