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From: telecom@eecs.nwu.edu (TELECOM Moderator)
Newsgroups: comp.dcom.telecom
Subject: Re: Illinois Bell Shows Real CLASS
Message-ID: <14100@accuvax.nwu.edu>
Date: 29 Oct 90 03:30:13 GMT
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X-Telecom-Digest: Volume 10, Issue 771, Message 3 of 11


Our two respondents in this issue both caught on quickly to the
*possible* way of ascertaining a calling number when Caller*ID is not
available. Unfortunatly, it does not work that way.

*60 # 01 # says one of two things:

   a) "The number you have added is a PRIVATE ENTRY."

   b) or, "I'm sorry, that number cannot be screened."

If the number is from out of LATA or otherwise unidentifiable to your
CO, then you get response (b). Otherwise you get (a). However, even
with (a) the number is not given to you. 

Regarding Call Screening generally, I've discovered several
interesting facts about our version of it. (Yes, your Moderator has
been busy playing with his new toys.) 

Having been told only about 60-70 percent of 312/708 and the portions
of 815 within our LATA have been converted, I decided to try and find
out which areas had not yet been cutover.  I found a few other things
in the process.

My testing procedure:

I dialed *60, then selected a prefix which came to mind from each of
the telepone areas here. For example, I tried 465 and 761 from here in
my own office, Chicago-Rogers Park.  I always added the same last
four digits '3000' for ease in remembering what had to later be
removed. 

There seemed to be only three or four areas where I could not screen,
one being Austin, the other being Evasnton/Skokie to my north, and
Newcastle in the far northwest area of the city.

By accident I found that if a number is not curently in service, it
cannot be added. Numbers which do not return supervision as we think
of it cannot be added. For example, 312-727 is used entirely by
Illinois Bell Headquarters. I could not add any 727 numbers to the
screen.

I was unable to screen 312-368-8000, the Illinois Bell Communicator
Newsline, yet I could screen other 368 numbers. I could not screen out
312-787-0000, which is how 911 gets translated for this neighborhood.

I was unable to screen numbers in any prefix above 9899.
Traditionally, the numbers from 9900 -> 9999 on any prefix here are
reserved for telco use. I was unable to screen 312-PIG anything, which
is the City of Chicago centrex, including the Police Department.
Possibly that is because from anywhere in Chicago, a call to one of
those numbers is only a single untimed unit, no matter how long you
talk, thus the 'supervision' is different than most. 

When you add a number to Call Screening, you apparently get all the
numbers in the group. I screened the listed number for my office,
which coincidentally is in the same CO as my residence. I screened
only the listed, first number in the series. To test it, I called in
via the WATS extender line, got the PBX, dialed 9 and went out again
to my number. *It screened the call* -- I know for a fact I was not
actually placing the call from the main listed, first number in the
group. I'd have been on one of the back-lines used for outgoing calls.
So apparently our Call Screening relies on the ANI it receives rather
than the specific number for the trunk used to place the call.
Apparently the ANI refers to all the numbers at our business by the
main number.

I could not screen either cell phone. I guess that is because my cell
phone numbers (312-415-xxxx and 312-504-xxxx) are just incoming DID
trunks. Smart me: I tried screening 312-228-xxxx, which is what ANI
reports is the number I am 'really' using when making a call out from
the cell phone. That could not be screened either, and a cross check
with the Name and Address Bureau showed the owner of 312-228-xxxx as
the 'IBT Co', no address listed, Hickory Hills, IL. Calls *to* that
number are intercepted saying 'the number you dialed, 228-xxxx is not
equipped for incoming calls'. 

One curious case: I tried screening 312-855-2000 and various other
lines up to 855-3100. I know these to be DID trunks and a Rolm system
in a department store downtown. The response I got from Call Screening
in every case in this group of numbers:

(After a longer than usual pause) "We're sorry, please try adding the
number again in a few minutes." ????

And I got that report at various times day and night over the past two
days. I have *no idea* why a 'few minutes' would make a difference. I
was able to add other 312-855 numbers (from 3101 up) immediatly. 

Finally, I was able to screen myself! :) I added my first (main
listed) number to the screen ... then tried dialing my first line from
my second line. It blocked me out, which re-inforces my belief that
our Call Screening here looks at the ANI given rather than the
individual phone number. I'd say that is a nice way of doing it.  

As I find further 'secrets' about Call Screening, I will post
messages. 


Patrick Townson