From: varney@cbnewsd.cb.att.com (Al Varney)
Subject: Re: ISDN and voice response systems
Organization: AT&T
Distribution: na
Date: Fri, 16 Oct 1992 05:31:11 GMT

In article <13329@bnr-rsc.UUCP> deand@bmerh404.BNR.CA (Dean Dillabough) writes:
>In article <13328@bnr-rsc.UUCP>, eswara@bnr.ca (Srinivas Eswara) writes:
>|>
>|>>All of the BRI sets that I have seen will generate DTMF from the keypad when
>|>>a call is answered. This is also the case for other sets such MBS or EBS
>|>>which use a proprietary digital interface.
>|>
>|>>-- 
>|>>++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>|>>|Michael Babineau           | BITNET: babineau@BNR.CA                    |
>|>>|Bell Northern Research Ltd.| UUCP  : ..!uunet!bnrgate!bmerh812!babineau |
>|>>|Ottawa, ON. CANADA         |         ..!psuvax!BNR.CA.bitnet!babineau   |
>|>>++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>|>
>|>The problem that I have seen is that some ISDN sets do not sustain the
>|>DTMF tone, causing problems for systems which expect the tone to be held for
>|>any length of time greater approx 1/2 a second. Of course, this is also
>|>a problem for a POTS set which cannot sustain the DTMF tone even if you
>|>keep the button pressed down.
>|>
>|>Srinivas Eswara
>|>Bell Northern Research Ltd.
>|>Ottawa, On. Canada
> 
> No DTMF was the problem I had with my ISDN phone. Real frustrating when you're
> put into those "Press 1 to get info on xxx, press 2 to talk to a sales-droid"
> phone systems. I finally gave up and used another guy's phone. He hadn't been
> blessed with an ISDN set yet... he may end up getting mine (remember
>this Seenu??)

   Yo, BNR folks (Dean, Srinivas and Michael).  I think your problem
might be your vendor .... :-)  Really.   Here's a free hint:

      Bellcore TR-TSY-000268, Sec. 2.2 {Assumptions}:
   "If end-to-end, inband signaling is required by the user, the user
   equipment is expected to send address information as DTMF signals over
   the B-channel. ... The user equipment is responsible for determining
   whether digits are sent as D-channel messages or DTMF signals on the
   B-channel.  However, the network will not expect any address information
   from the user after sending the user a CALL PROCeeding message, without
   subsequently providing the user a prompt over the D channel."

   Requirements for the telephone network say DTMF as short as 40 msec.
should be recognized -- since facilities, etc. might distort that somewhat,
the CPE needs to use more than 55 msec., cleanly.  But I don't understand
why any CPE (and especially ISDN sets) wouldn't send DTMF as long as the
keypad was depressed.  Ours certainly do.

   On the other hand, 1/2 second seems like a LONG time to need to lean
on the key -- are these real cheap systems that need that long???

   Last comments -- Does Canada allow non-TELCo VR systems that don't
send answer?  And do sales offices really operate VR systems that don't
time-out for all those Dial Pulse users?


  And just to complete the thread:

 peterd@pjd.dev.cdx.mot.com (Peter Desnoyers) wrote (in another article):

>>In article <peterd.719082854@pjd.dev.cdx.mot.com> peterd@pjd.dev.cdx.mot.com (Peter Desnoyers) writes:
>>>
>>>Interestingly enough, even if you have ISDN phones on both ends you are
>>>still probably going to have to send DTMF tones to send keypress
>>>information.

>Third, I find it ironic that if we ever do migrate to ISDN in a few 
>decades, your phone will still probably be generating DTMF tones whenever
>you deal with an ACD or voicemail system.

   In a few decades, keypads will be out, and voice recognition,
portable interfaces with your own personal directory, etc. will be in.

   Bellcore's TR-TSY-000866 {ISDN Message Service} supports the use
of packet-mode (D- or B-channel) to interact with Message Systems.
It also allows packet-mode callers to leave messages, etc.  If you
think about it, a system that still uses the KEYPAD for interaction
will be the archaic thing, not the tones generated by them.  DTMF is
still pretty good if you limiting yourself to a 12-key keypad.  I don't
see the advantage of encoding the key presses into IE and Q.931, shipping
it over SS7, and decoding them at the far end -- DTMF is easier & cheaper.
If you are going to use the D-channel for interaction, think beyond the
"0 for yes, 1 for no, 9 to disconnect" era.

Al Varney - just MY opinion.
Newsgroups: comp.dcom.isdn