Phoneline Diverter

[hepcatbrandon]

Hi everyone. I've just begun to learn about electronics and wanted to
try my hands at making a diverter (or rather a variation on a design
that I found), and I could use some help. The purpose of this circuit
is to connect two phone lines together so that when you call LINE 1
you get the dial tone of LINE 2 and can send DTMF and talk just as if
you had dialed out of LINE 2 directly. I appologize in advance for my
butt-ugly illustrations (see links) and general newbiness; the
drawings are meant to just show the basic logic, as that's enough for
me to worry about at the moment.

This is the first sketch I came up with:

To explain: In the position shown, both lines 1 and 2 are "on hook". I
dial up the number for LINE 1, the CO sends AC (ringing) current to
line 1 and the capacitor allows current to flow into the full wave
bridge rectifier, sending DC through the relay.
This closes both circuits in LINES 1 and 2, LINE 1 stops "ringing" and
allows DC to flow through LINE 1 and through LINE 2. Now it is LINE 2
that is keeping the relay open. Both lines are now "off hook".
The gold blotch represents the undefined connection between the two
lines that is the purpose of the circuit. I have been trying to find
information about DC coupling but it all seems very complicated. The
design that I initially found used a 600ohm-600ohm transformer, but is
there an easier way? what would happen if you connected them with a
bit of wire?
Now when the call is completed and whoever LINE 2 calls hangs up, the
CO will initiate a polarity reversal on LINE 2 that will cause the
circuit to collapse and reset. There is a problem if LINE 2 dials
something that never hangs up, however...

Which leads me to v0.2:

Now this may be crazy, I don't know. But in this design, when the
relay is thrown, LINES 1 and 2 are connected in a figure eight or
infinity symbol shape, with RING of LINE 1 flowing into TIP of LINE 2
and vice versa. This way, a polarity reversal on either end will reset
the circuit and I don't have to learn about coupling.

Does either design make sense? If not why? Any advice you can give me,
even to tell me what to go about reading into would be great.
Thanks

 

[Andrew Holme]

Hi everyone. I've just begun to learn about electronics and wanted to
try my hands at making a diverter (or rather a variation on a design
that I found), and I could use some help. The purpose of this circuit
is to connect two phone lines together so that when you call LINE 1
you get the dial tone of LINE 2 and can send DTMF and talk just as if
you had dialed out of LINE 2 directly. I appologize in advance for my
butt-ugly illustrations (see links) and general newbiness; the
drawings are meant to just show the basic logic, as that's enough for
me to worry about at the moment.

This is the first sketch I came up with:

http://jupiter.walagata.com/w/jberryman/gold_box_illustration_copy.jpg[
/img]

To explain: In the position shown, both lines 1 and 2 are "on hook". I
dial up the number for LINE 1, the CO sends AC (ringing) current to
line 1 and the capacitor allows current to flow into the full wave
bridge rectifier, sending DC through the relay.
This closes both circuits in LINES 1 and 2, LINE 1 stops "ringing" and
allows DC to flow through LINE 1 and through LINE 2. Now it is LINE 2
that is keeping the relay open. Both lines are now "off hook".
The gold blotch represents the undefined connection between the two
lines that is the purpose of the circuit. I have been trying to find
information about DC coupling but it all seems very complicated. The
design that I initially found used a 600ohm-600ohm transformer, but is
there an easier way? what would happen if you connected them with a
bit of wire?
Now when the call is completed and whoever LINE 2 calls hangs up, the
CO will initiate a polarity reversal on LINE 2 that will cause the
circuit to collapse and reset. There is a problem if LINE 2 dials
something that never hangs up, however...

Which leads me to v0.2:

[img]http://jupiter.walagata.com/w/jberryman/gold_box_2_copy.jpg

Now this may be crazy, I don't know. But in this design, when the
relay is thrown, LINES 1 and 2 are connected in a figure eight or
infinity symbol shape, with RING of LINE 1 flowing into TIP of LINE 2
and vice versa. This way, a polarity reversal on either end will reset
the circuit and I don't have to learn about coupling.

Does either design make sense? If not why? Any advice you can give me,
even to tell me what to go about reading into would be great.
Thanks

In your second diagram, one of the diodes is short circuited by the red and
blue wires from the bottom end of the relay coil.

You must use the transformer.

Step 1 - Try it with just the transformer and two switches.
Step 2 - Prototype a ring detector and get that bit working in isolation.
Step 3 - Replace the switches with relays and get it working so they latch
on permanently.
Finally - step 4 - deal with the disconnection problem. Can you make a
polarity reversal detector with relays and diodes?

I hope you're not planning to make telephone calls at someone else's expense

 

[Dbowey]

jberryman posted:

<<

(snip)

Now when the call is completed and whoever LINE 2 calls hangs up, the CO will
initiate a polarity reversal on LINE 2 that will cause the circuit to collapse
and reset.

(snip)
Why do you think the CO will initiate a polarity reversal?

Your diagram doesn't make much sense.

Don

 

[Pooh Bear]

Hi everyone. I've just begun to learn about electronics and wanted to
try my hands at making a diverter (or rather a variation on a design
that I found), and I could use some help. The purpose of this circuit
is to connect two phone lines together so that when you call LINE 1
you get the dial tone of LINE 2 and can send DTMF and talk just as if
you had dialed out of LINE 2 directly.

I haven't a clue what you're on about but be aware that anything connected to the
PSTN ( public switched telephone network ) has to be approved - certainly here in the
UK.

If you have 2 lines and want to connect various stuff get a cheap PABX.


Graham

 

[hepcatbrandon]

Hi everyone. I've just begun to learn about electronics and wanted to
try my hands at making a diverter (or rather a variation on a design
that I found), and I could use some help. The purpose of this circuit
is to connect two phone lines together so that when you call LINE 1
you get the dial tone of LINE 2 and can send DTMF and talk just as if
you had dialed out of LINE 2 directly. I appologize in advance for my
butt-ugly illustrations (see links) and general newbiness; the
drawings are meant to just show the basic logic, as that's enough for
me to worry about at the moment.

This is the first sketch I came up with:

To explain: In the position shown, both lines 1 and 2 are "on hook". I
dial up the number for LINE 1, the CO sends AC (ringing) current to
line 1 and the capacitor allows current to flow into the full wave
bridge rectifier, sending DC through the relay.
This closes both circuits in LINES 1 and 2, LINE 1 stops "ringing" and
allows DC to flow through LINE 1 and through LINE 2. Now it is LINE 2
that is keeping the relay open. Both lines are now "off hook".
The gold blotch represents the undefined connection between the two
lines that is the purpose of the circuit. I have been trying to find
information about DC coupling but it all seems very complicated. The
design that I initially found used a 600ohm-600ohm transformer, but is
there an easier way? what would happen if you connected them with a
bit of wire?
Now when the call is completed and whoever LINE 2 calls hangs up, the
CO will initiate a polarity reversal on LINE 2 that will cause the
circuit to collapse and reset. There is a problem if LINE 2 dials
something that never hangs up, however...

Which leads me to v0.2:

Now this may be crazy, I don't know. But in this design, when the
relay is thrown, LINES 1 and 2 are connected in a figure eight or
infinity symbol shape, with RING of LINE 1 flowing into TIP of LINE 2
and vice versa. This way, a polarity reversal on either end will reset
the circuit and I don't have to learn about coupling.

Does either design make sense? If not why? Any advice you can give me,
even to tell me what to go about reading into would be great.
Thanks

Thanks a bunch, Andrew, for the input. This project is just for fun...
there are easier ways to make free calls.

Don, the polarity reversal is the disconnect signal at least here in
the US. You know how when you stay on the line for a few seconds after
someone has hung up, you hear a click then another click then dial
tone? If you could take a minute to tell me what doesn't make sense
about the drawing, I'd appreciate it.

Graham, find me a PBX that can fit in the palm of your hand and costs
five bucks and I'll glad to dish out the money. And sucks to BT.

 

[Dbowey]

jberryman posted:

(snip)

<< Don, the polarity reversal is the disconnect signal at least here in
the US. You know how when you stay on the line for a few seconds after
someone has hung up, you hear a click then another click then dial
tone? If you could take a minute to tell me what doesn't make sense
about the drawing, I'd appreciate it.
I helped write the ANSI Standard for loop-start and ground=start (POTS)
telephone service, and it does not provide for a disconnect polarity reversal.

So I ask again; where did you obtain the information that it does? I saw
another post on another board where the poster was also positive there is a
polarity reversal.

As to the drawing; I didn't consider it any further than seeing one of the
diodes shorted permanently by the wiring.

Don

 

[hepcatbrandon]

jberryman posted:

(snip)

<< Don, the polarity reversal is the disconnect signal at least here in
the US. You know how when you stay on the line for a few seconds after
someone has hung up, you hear a click then another click then dial
tone? If you could take a minute to tell me what doesn't make sense
about the drawing, I'd appreciate it.

I helped write the ANSI Standard for loop-start and ground=start (POTS)
telephone service, and it does not provide for a disconnect polarity reversal.

So I ask again; where did you obtain the information that it does? I saw
another post on another board where the poster was also positive there is a
polarity reversal.

As to the drawing; I didn't consider it any further than seeing one of the
diodes shorted permanently by the wiring.

Don

Well then, I humbly retract my statement. I remember reading about a
polarity reversal before this, but I most recently got this
information from a phreaking text file on plans for a diverter, which
I had based my design sketches on. The article can be found here:

http://mvb.saic.com/freeware/vmslt99b/phrack/phn-diverter.txt

Here is another example of an article I had lying around in which
polarity reversal is mentioned:
"There is no guaranteed (single) way to determine when a call was
terminated at the far end. Depending on the switch type you need to
look at loop break (loss of loop current), change of DC polarity, dial
tone, stutter dial tone, and/or silence. If you want to do something
for unknown lines on unknown switches then you will need a combination
of the above."

(from http://www.epanorama.net/circuits/teleinterface.html )

Perhaps this depends on the particular switch serving the phone? Or is
this assumption completely false? If so what takes place on the line
between the time the called party hangs up and you are sent dial tone
again?

Thanks

 

[Rich Grise]

Well then, I humbly retract my statement. I remember reading about a
polarity reversal before this, but I most recently got this
information from a phreaking text file on plans for a diverter, which
I had based my design sketches on. The article can be found here:

http://mvb.saic.com/freeware/vmslt99b/phrack/phn-diverter.txt

Here is another example of an article I had lying around in which
polarity reversal is mentioned:
"There is no guaranteed (single) way to determine when a call was
terminated at the far end. Depending on the switch type you need to
look at loop break (loss of loop current), change of DC polarity, dial
tone, stutter dial tone, and/or silence. If you want to do something
for unknown lines on unknown switches then you will need a combination
of the above."

(from http://www.epanorama.net/circuits/teleinterface.html )

Perhaps this depends on the particular switch serving the phone? Or is
this assumption completely false? If so what takes place on the line
between the time the called party hangs up and you are sent dial tone
again?

I can't understand why you don't simply call the phone company and ask
them. They know the answers to all of these questions.

Of course, all of your questions make a lot more sense if you're just
trying to pull a fast one.

Good Luck!
Rich

 

[Dbowey]

jberryman posted:

<< [email protected] (Dbowey) wrote in message

jberryman posted:

(snip)

<< Don, the polarity reversal is the disconnect signal at least here in
the US. You know how when you stay on the line for a few seconds after
someone has hung up, you hear a click then another click then dial
tone? If you could take a minute to tell me what doesn't make sense
about the drawing, I'd appreciate it.

I helped write the ANSI Standard for loop-start and ground=start (POTS)
telephone service, and it does not provide for a disconnect polarity reversal.

So I ask again; where did you obtain the information that it does? I saw
another post on another board where the poster was also positive there is a
polarity reversal.

As to the drawing; I didn't consider it any further than seeing one of the
diodes shorted permanently by the wiring.

Don

Well then, I humbly retract my statement. I remember reading about a
polarity reversal before this, but I most recently got this
information from a phreaking text file on plans for a diverter, which
I had based my design sketches on. The article can be found here:

http://mvb.saic.com/freeware/vmslt99b/phrack/phn-diverter.txt

Here is another example of an article I had lying around in which
polarity reversal is mentioned:
"There is no guaranteed (single) way to determine when a call was
terminated at the far end. Depending on the switch type you need to
look at loop break (loss of loop current), change of DC polarity, dial
tone, stutter dial tone, and/or silence. If you want to do something
for unknown lines on unknown switches then you will need a combination
of the above."

(from http://www.epanorama.net/circuits/teleinterface.html )

Perhaps this depends on the particular switch serving the phone? Or is
this assumption completely false? If so what takes place on the line
between the time the called party hangs up and you are sent dial tone
again?
--

Thanks for the links.

The first one, about the diverter, is a conglomerate of bad information,
especially the theft of service suggestion of tapping another person's phone
line for use by the diverter to place an outgoing call. That's a Federal crime
and *will* land a person in jail for a year or more when caught.

The author "suggests" that on disconnect, a polarity reversal may be received.
Well, that's one major problem of the internet: Bad information grows in
acceptance.

The second link also mentions polarity reversal as a possibility, but.......

It may be the authors are misguided by knowing there are telephone *Trunks*
(not lines like POTS service) which do use loop polarity reversal in their
operating states. These are commonly used to provide Central Office services
to a PBX or other Multifunction terminal equipment.

You ask what does happen. Modern switching machines *may* remove the DC
voltage from the line for short periods while it "prepares" to complete the
disconnect. These are called "Open Switch Intervals (OSI). A single OSI will
not exceed 350 ms in length and if another follows it, there will be at least
100 ms before the start of the new one. You may want to examine the signals on
your line to see if this is usable.

Manufacturers of Answering Sets frequently use absence of speech detection to
decide it should hang-up. This is because there is no intentional "disconnect
signal" sent to the called-party end other than eventual dialtone.

Don

 

[Andrew Holme]

hepcatbrandon wrote:
[snip]

Well then, I humbly retract my statement. I remember reading about a
polarity reversal before this, but I most recently got this
information from a phreaking text file on plans for a diverter, which
I had based my design sketches on. The article can be found here:

http://mvb.saic.com/freeware/vmslt99b/phrack/phn-diverter.txt

Here is another example of an article I had lying around in which
polarity reversal is mentioned:
"There is no guaranteed (single) way to determine when a call was
terminated at the far end. Depending on the switch type you need to
look at loop break (loss of loop current), change of DC polarity, dial
tone, stutter dial tone, and/or silence. If you want to do something
for unknown lines on unknown switches then you will need a combination
of the above."

(from http://www.epanorama.net/circuits/teleinterface.html )

In your original post you mention detecting disconnection of either line. I
think you only need to detect disconnection of the incoming / originating
line because the originator alone should control the call. Since there is
no guaranteed way to determine when a call was terminated at the far end,
the best you can do is rely on observed behaviour. You could do an
experiment to see if your local exchange provides either a polarity reversal
or a momentary loop break.

 

[Rich Grise]

hepcatbrandon wrote:
[snip]

Well then, I humbly retract my statement. I remember reading about a
polarity reversal before this, but I most recently got this
information from a phreaking text file on plans for a diverter, which
I had based my design sketches on. The article can be found here:

http://mvb.saic.com/freeware/vmslt99b/phrack/phn-diverter.txt

Here is another example of an article I had lying around in which
polarity reversal is mentioned:
"There is no guaranteed (single) way to determine when a call was
terminated at the far end. Depending on the switch type you need to
look at loop break (loss of loop current), change of DC polarity, dial
tone, stutter dial tone, and/or silence. If you want to do something
for unknown lines on unknown switches then you will need a combination
of the above."

(from http://www.epanorama.net/circuits/teleinterface.html )

In your original post you mention detecting disconnection of either line. I
think you only need to detect disconnection of the incoming / originating
line because the originator alone should control the call. Since there is
no guaranteed way to determine when a call was terminated at the far end,
the best you can do is rely on observed behaviour. You could do an
experiment to see if your local exchange provides either a polarity reversal
or a momentary loop break.

I've suggested asking the phone company at least twice. Apparently he
doesn't want them to know what he's up to.

Thanks,
Rich

 

[hepcatbrandon]

--

Thanks for the links.

The first one, about the diverter, is a conglomerate of bad information,
especially the theft of service suggestion of tapping another person's phone
line for use by the diverter to place an outgoing call. That's a Federal crime
and *will* land a person in jail for a year or more when caught.

The author "suggests" that on disconnect, a polarity reversal may be received.
Well, that's one major problem of the internet: Bad information grows in
acceptance.

The second link also mentions polarity reversal as a possibility, but.......

It may be the authors are misguided by knowing there are telephone *Trunks*
(not lines like POTS service) which do use loop polarity reversal in their
operating states. These are commonly used to provide Central Office services
to a PBX or other Multifunction terminal equipment.

You ask what does happen. Modern switching machines *may* remove the DC
voltage from the line for short periods while it "prepares" to complete the
disconnect. These are called "Open Switch Intervals (OSI). A single OSI will
not exceed 350 ms in length and if another follows it, there will be at least
100 ms before the start of the new one. You may want to examine the signals on
your line to see if this is usable.

Manufacturers of Answering Sets frequently use absence of speech detection to
decide it should hang-up. This is because there is no intentional "disconnect
signal" sent to the called-party end other than eventual dialtone.

Don

Don, thanks a bunch for helping to clear that up for me. Since the
author of that file seemed sure that his device worked I'm assuming he
tested it and an OSI is what caused the circuit to reset, rather than
a reversal in polarity.
________
Andrew, I think I understand what you are saying, but for whichever
end of the circuit "listens" for some kind of disconnect signal, the
signal will be the same. You see the structure of a call through the
circuit would look like this:

(caller)<---->[telco]<--->(diverter circuit)<--->[telco]<--->(called)

so either way, the resetting of the circuit must come from some change
initiated by the telco.
_________

[snip]
I've suggested asking the phone company at least twice. Apparently he
doesn't want them to know what he's up to.
[/snip]

Um... first of all, you suggested it once, and while it was a good
suggestion, the way in which you expressed it (by implying that I'm
some kind of criminal) was both obnoxious and offensive. So I didn't
waste my time in responding.

____________________________

Thanks all for the suggestions!
JB