From: bender@oobleck (Duke of Canterbury)
Newsgroups: comp.dcom.modems
Subject: Re: The Zen of CID
Date: 15 Oct 92 20:56:12 GMT
Reply-To: bender@oobleck.eng.sun.com
Organization: SPARK's R US
NNTP-Posting-Host: oobleck
X-Newsreader: Tin 1.1 PL3

pdivine@unixg.ubc.ca (Patrick Devine) writes:
: In article <1bfs5lINN54n@usenet.INS.CWRU.Edu> al045@cleveland.Freenet.Edu (Gergely Tapolyai) writes:
: >
: >First:  How does a switching station makes sure that the CID that
: >is already on the line is _valid_.
: 
: CID is conceptualy very easy.

Yes it is, but you obviously have no idea how it works.  I have never seen
such a load of crap posted in such an authoritive manner!  You have no idea
what you are talking about!  Instead of exercising your fingers posting this
drivel, why not ask a question instead like "I don't know how CID works,
would someone be so kind as to tell me?"!

: Party 1 picks up his or her phone and
: decides to make a phone call to Party 2.  After the phone has been dialed,
: it connects to the main office (or switching network, or whatever).  The
: main office computer has a list of all of its subscribers/whatever.  The
: computer database figures out Party 1's phone number, and then patches the
: call through to Party 2, and places the data packet with the CID
: information on the end of the ring.  Party 2's CID machine interprets the
: information sent and can figure out who is calling beforehand.
:
: I'm assuming that the switching station where the call is being placed
: through does not interupt the ring signal already put into place at the
: head office, it just amplifies it so it doesn't degrade in quality.

No, no, no, no, no.  You have NO IDEA how the phone system works.  In order
for CID to reach you, all of the switches between the calling party and the
called party must be digitial switches running an inter-switch protocol
called SS7.  With these switches, the ring that you hear is generated LOCALLY
in your switch, and is not the ring generated by the far end switch.

: >Is it possible to make a little "black box" that will allow you to 
: >put any CID on your outgoing call and noone will ever discover it?
: 
: masking you phone number is very plausible,
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Nope.  You have NO CONTROL what your local switch sends to the remote switch.

: and I'm sure there are box schematics out there to do it.

Sure, like those idiotic schematics that show you how to turn your 2400 baud
modem into a V.32bis modem by replacing a ROM and wiring a pot across the
black and yellow leads of the phone jack.

: I'm sure you could even mask your phone
: number well enough that your phone company does not even know who is
: placing the call.  (free long distance calls?)

Uh, huh.

: >You have to figure, that CID came thorugh over a 100 switches 
: >probably and you cannot tell me that ever one of them was up to date
: >with the latest technology?  I see no way for phone companies to
: >sync their systems, nor can I see a verification at every switch
: 
: again, I beleive that it doesn't matter if the middle switching system
: isn't good enough to support CID.  As long as the originating and answering
: switching networks are capable.

Get a copy of the CID specs and read and UNDERSTAND it before you post this
pseudo-intellectual crap again, please.  The CID (audio) data that your CID
box "hears" between the first and second ring is generated AT YOUR LOCAL
SWITCH and does NOT travel over the network as analog audio.

mike

--
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    Grashopper, you have been many years in the training, and I grow old,
    expecting the day when I receive the SIGXCPU, and _exit this world.
    I see that you are ready.
Newsgroups: comp.dcom.modems