Caller ID experiment results

Caller ID experiment results

Post by Shawn4s » Tue, 08 Nov 1994 11:18:57

I tried to do a basic Caller ID experiment being it makes for a great
weekend education project...  A phone cord consists of a red (power?),
black (ground?), yellow and green wire and the RCA jack consists of a red
(positive) and a black (ground)...  How to wire this all up together?  I
didn't have a clue.  I tried a few ways, keeping black and black connected
and attempting to call myself after connecting the various phone cord
colors to the red RCA wire.  None of them phased my Caller ID box.  

My for-now conclusion:   as I have noticed nothing different in the way my
cordless sounds, from the scanner's point of view, since the service came
into my area (no tone bursts or anything new over the air) and the Caller
ID box goes inline first from the wall before ever reaching your phone
and/or answering machine, I would have to say that the Caller ID
information is sent through one of the wires, never reaching the cordless
phone...  Unless the cordless base had a built-in Caller ID feature (some
do now), I would think there would be no need or ability for a regular
cordless to ever "hear" the information anyway...  But even if the Caller
ID feature _was_ built into the cordless though, it would have to be
"broadcast" to the handset or base. In either case, I don't think that's
how the technology works...  I'm sure it's a wire thing...

:-(

Shawn

 
 
 

Caller ID experiment results

Post by Glynne Tol » Tue, 08 Nov 1994 13:01:35


Caller ID works like this:

Between the first ring and the second ring a data burst with the ID
info occours.  It is exactly the same as a 1200 baud modem.  You could
even modify a 1200 baud (or greater) modem to not hold the line off-hook
and monitor the phone line.  Unless cordless phones are designed to detect
caller ID, that data will NOT be broadcasted.  Since the base needs to
detect the 90v pulses for the ring and convert them to a data burst
the handset is designed to detect and then simulate a ring.  If you try
moding a modem for this (a simple .47pf cap. at the phone line end
of the isolation transformer ought to do it) just set you comm software
for 8n1/1200 baud and there should be no need to decode it.  It comes
out as ASCII (with a little bit of noise from the ring signal on either
side of the data burst).  Happy hacking!

 
 
 

Caller ID experiment results

Post by David B Bak » Tue, 08 Nov 1994 19:04:37

: Caller ID works like this:
: info occours.  It is exactly the same as a 1200 baud modem.  You could
: even modify a 1200 baud (or greater) modem to not hold the line off-hook
: and monitor the phone line.  Unless cordless phones are designed to detect
(snip)
: the handset is designed to detect and then simulate a ring.  If you try
: moding a modem for this (a simple .47pf cap. at the phone line end
: of the isolation transformer ought to do it) just set you comm software
: for 8n1/1200 baud and there should be no need to decode it.  It comes

Wow Glynne, sounds like you've done your homework! As I have not, could
you explain a little more about the placement of the capacitor. I'd like
to try it, but I'd like a little more info before I start.
 Thanks,
Dave

 
 
 

Caller ID experiment results

Post by Shal » Wed, 09 Nov 1994 02:22:54



>I tried to do a basic Caller ID experiment being it makes for a great
>weekend education project...  A phone cord consists of a red (power?),
>black (ground?), yellow and green wire and the RCA jack consists of a red
>(positive) and a black (ground)...  How to wire this all up together?  I
>didn't have a clue.  I tried a few ways, keeping black and black connected
>and attempting to call myself after connecting the various phone cord
>colors to the red RCA wire.  None of them phased my Caller ID box.  

(snip)
>Shawn

The wires you are using aren't the right pairings. The red goes with the
green, and the yellow with the black. I believe the red is the negative
and the green is the positive (go yell at Western Electric for reversing
the conventional red=hot arrangement). At one time the yellow was used for
the input to the ringer; some old phones I have found will not ring unless
you connect the yellow and green wires together (INSIDE the phone, not at
the jack.) These are the old W.E. phones with the mechanical ringers. On
a modern setup, the yellow wire is only used as the (+) terminal for a second
line on a two-line jack (with the black being the (-) terminal). If you
have only one line, there won't be anything even connected to the black wire
in the wall jack.
Note also that a dial phone with a mechanical ringer doesn't care about
the polarity; it's only needed for a Touch-Tone or other electronic-type
--


||===============||==============Steven Wright=||NYC Locksmith License 824141
 
 
 

Caller ID experiment results

Post by Glynne Tol » Wed, 09 Nov 1994 05:50:39


: Wow Glynne, sounds like you've done your homework! As I have not, could
: you explain a little more about the placement of the capacitor. I'd like
: to try it, but I'd like a little more info before I start.
:  Thanks,
: Dave

Well, I only know this by theory rather then fact, I must confess.  I've
not tried this myself.  You can find a cheap slow modem these days.

        ____| |_______    ___________________
            | |       >||<
                      >||<
        from phone    >||<
          line        >||<
        ______________>||<__________________

                       transformer inside modem

You will likely have to cut a trace on the PC board to fit it in there.
(or place the cap in the phone line going to the modem)

Send an ATS1=1 might fix it to look for the data burst.

As you can tell, I don't do documentation!  Hope that clears this up.

Oh, I also have a gif on how to make a RS-232 interface to a caller ID
box for anyone interested.

 
 
 

Caller ID experiment results

Post by Shawn4s » Wed, 09 Nov 1994 07:35:34

Well Glynne, where were you when I needed you?  :-)

There's the answers folks!  No wonder I didn't get a thing...

:-)

Shawn

(shuffle, shuffle) "Modem...?  Now where'd I put my old modem...?"

 
 
 

Caller ID experiment results

Post by Shawn4s » Sat, 12 Nov 1994 07:55:28

I'll try the wiring info shown here and see if, by chance, it shows the
numbers on my Caller ID box...

I'll report my findings.

:-)

Shawn