From: dtlai@srv.PacBell.COM (Danh Lai)
Newsgroups: ba.internet
Subject: Re: ISDN, PacBell, phone charges, USENET and you
Date: 29 Sep 92 16:29:07 GMT
Organization: Pacific * Bell

In article <ERIC.92Sep28175110@iceland.telebit.com> eric@telebit.com (Eric Smith) writes:
>
>Feature package C does let you use both B channels for data, but I was
>complaining that it only lets you use one B channel for voice (according to
>my Pac Bell rep; I haven't tried it).
>
See if I can address your concern (please hack it out to verify :)).
Theoretically, voice channel can't be used for data but data channel can always
be used for voice. The reason being that we apply bit stealing in digital voice
trunk to perform answer supervision. This goes beyond stealing 1 bit out of
every 8 bits for signaling that cut down inter-office trunk throughput from 64 kbps
down to 56 kbps; within the 56 kbps, addition bits are stolen to perform answer
supervision on that particular voice connection. When your specify the channel
to be data, you are getting a true 56 kbps clear channel on inter-office trunk,
hence, you should be able to transmit voice through this channel as well.

>I don't understand what the point is of not letting you use either B channel
>for whatever you want.
>
This doesn't make sense to me either if it's true. One of the problem we have in
promoting ISDN is that we don't have enough knowledgeable rep to spread the
words and many times it's safer to say NO :(.

>By the way, someone told me that with package C you get a separate phone
>number for each B channel.  I guess if I want two people to be able to call
>me simultaneous using the same phone number, I have to set it up as a hunt
>group.  This is fine for Centrex,  but once they get a residential tarriff
>how will I do that?
>
It's true that you get separate phone # for each of the B channel. Actually,
it's better already, it's used to be 4 Directory (phone) Numbers (DNs)
associates with each BRI to provide SIGNUM for the data call! All the signaling
are done via out of band thru the D channel and the 2 B channels are distict so
there should not be any contention if 2 calls arrive simultaneously. If you have
an ISDN phone set, the signaling of the second call that arrive can be either an
LED flashing or a display message on your LED displays that post the call info.
delivered to the set via the D channel. YOU DON'T HAVE TO SET IT UP AS A HUNT
GROUP. In the case of multiple call appearance, you assign the same DN to
multiple buttons, it works similar to call waiting but better because only you
see the incomming call notification and there can be more than 2 calls that you
can take at the same time. REMEMBER, all signaling are done out of band via the
D channel!

Most of the ISDN switches support passive bus arrangement, that is you can hook
up multiple devices to the same S-bus.  This capability allows you to hook up 2
physical ISDN phone set and a computer or any combination of upto 8 devices to
share the 2B+D channel. There is a California ISDN User Group (CIUG??) that is
chair by some guy at LLL (Lawrence Livermore Lab). You can check this group out
to get more info.

Cheers,
Danh Lai
>Eric


-- 
======================= P A C I F I C  *  B E L L =========================
| Danh T. Lai                      |  Phone # (510) 901-9947              |
| email   dtlai@pacbell.com        |                                      |
===========================================================================