From: cstorry@gandalf.ca (Chuck Storry)
Subject: Re: Subaddressing (was: ISDN/analog interfacing)
Organization: Gandalf Data Ltd.
Date: Thu, 28 Jan 1993 14:42:37 GMT

In <1993Jan27.123439.21824W@lumina.edb.tih.no> ketil@edb.tih.no (Ketil Albertsen,TIH) writes:

>In article <C1HpEy.5Go@sranhd.sra.co.jp>, nisimura@sran233.sra.co.jp (Tohru 
>Nishimura) writes:

>>[...] ISDN exchange can detect which
>>type equipments are attached to customer ISDN busline, and ISDN exchange
>>subsystem will answer as "There is no equipment you can talk with....."
>>IN THE CASE OF caller is ordinal analog telephone system.

>How can the exchange know? Functionality depends on the hardware and 
>software loaded into my PC at the moment. I may unplug the speaker and 
>microphone from my PC and delete the driver program for the voice 
>functions, but leave the file transfer and email software running; I 
>will not report that to the exchange. My ISDN interface card is the 
>same, so there is no electrical change that can be detected on the busline.

>The only way presence of voice (or other kinds) of functionality can be
>detected is by asking my PC (by sending a SETUP) message: Do you WANT to
>accept this incoming voice call? If my PC responds with an ALERTING
>message, then the exchange may assume that I do have the necessary
>equipment and software. But the converse is NOT true: I may have it,
>but not WANT to utilize it at the moment. Eg. I may want to remain
>quiet to calls from telemarketing companies. I may want to remain quiet
>to most calls (only accept calls from selected callers) after 11 p.m.

>If there is any way that the exchange can detect which functionality
>my PC-with-ISDN-card realizes in its software, then I haven't read the
>ISDN recommendations close enough. Also, I will be scared. What else
>does the exchange know about my PC software??  :-)

I think that some of the management procedures being considered for NI-2 
and certainly beyond include the concept of compatibility matching. This
consists of the ability of the CO to tell the TA how the line is configured
and i believe the converse could also be possible. (parameter download) 
 Us techies tend to invent these things without always considering all the
concerns however I tend to support any mechanism that facilitates a plug
and play ISDN service. Have you ever tried to answer all the questions a
service provider asks then match it to the terminal's specs (or worst
Yet have a look at the consoles of a 5E or DMS100 and get CALL APPEARANCES,
FEATURE KEYS,DIRECTORY NUMBERS, SPIDS, BEARER CAPABILITIES allowed, CALLING
NUMBER PRESENTATION allowed and so on to match the terminal's capability?

I know the DMS already supports a "proprietary" version of the download
of BRI configuration called SPM. All parameters associated with the SPID
are downloadable at the request of the terminal. We use this in our 
Northern Proprietary mode of our TAs in order to get the Directory Number.
It seemed bad enough to ask the user to program a thing called a SPID but
then to also ask for DN, CALL APPEARANCES, FEATURE KEYS ... was a bit much.

Unfortunately NI-1 is the lowest common denomonator so we're back to forcing
the user to manually configure all these things.

Back to my point: on first connecting to the line there exists (at least
in north american ISDN) the requirement to initialize/identify the terminal
which ultimately can (and probably will) support bidirectional querying of
Opposite end capabilities (specifically as they relate to ISDN).

Chuck.
-- 
Chuck Storry, Principal Designer      CAnet: cstorry@gandalf.ca
Gandalf Data Ltd.                     Voice: (613) 723-6500
130 Colonnade Rd So, Nepean, Ontario  Fax: (613) 226-1717
Canada  K2E 7M4