URGENT question on draft-ietf-avt-tones-07
Gunnar Hellstrom
gunnar.hellstrom at OMNITOR.SE
Sat Feb 12 07:36:18 EST 2000
Steve and all,
Thank you for making the observation of the double nature of CRd and MRd.
The same cahnges as you have done, I need to do in the Call Type
Discrimination package of H.248 discussed now in SG16.
When looking through avt-tones, I saw that the example showing different
signals displayed V.21 bits 10 times longer than they usually are.
This is the table from avt-tones-07
------------------------------Table with
errors---------------------------------------
Tone name frequency on period off period
______________________________________________________
CNG 1100 0.5 3.0
V.25 CT 1300 0.5 2.0
CED 2100 3.3 --
ANS 2100 3.3 --
ANSam 2100*15 3.3 --
V.21 "0" bit, ch. 1 1180 0.033
V.21 "1" bit, ch. 1 980 0.033
V.21 "0" bit, ch. 2 1850 0.033
V.21_"1"_bit,_ch._2________1650______0.033____________
ITU dial tone 425 -- --
U.S. dial tone 350+440 -- --
______________________________________________________
ITU ringing tone 425 0.67--1.5 3--5
U.S._ringing_tone_______440+480________2.0_________4.0
ITU busy tone 425
U.S. busy tone 480+620 0.5 0.5
______________________________________________________
ITU congestion tone 425
U.S. congestion tone 480+620 0.25 0.25
Table 7: Examples of telephony tones
----------------------------------------------------------------------------
------------------
If the V.21 bits are aiming at being used for 300 bit/s V.21, that is the
most common case, they should be specified to have a length of 0.0033 or
rather 0.00333 seconds if you can support that precision.
Agree?
-----
Comment on your original topic - the V.8 bis signals.
In your message, you have 1375 Hz and 1357 Hz. They should both be the same
and be 1375. That is also correct in avt-tones-07, so - no problem.
About timing of these tones, V.8 bis is a bit fuzzy,saying that 400 ms is
preferred but for some cases, not to cause interworking problems with
existing devices it can be reduced to 280 ms. I do not know what is behind
that, and do not understand how the DCE can select between these two cases,
so I hope that your single timing of 400 ms is OK. Maybe Bruce Adams,
rapporteur of Q4/16 and in charge of V.8 bis maintenance can comment on
that.
-----
Regards
Gunnar Hellström
> -----Original Message-----
> From: casner at cisco.com [mailto:casner at cisco.com]
> Sent: Friday, February 11, 2000 10:40 PM
> To: rem-conf at es.net; ITU-SG16 at mailbag.cps.intel.com
> Cc: Henning Schulzrinne
> Subject: URGENT question on draft-ietf-avt-tones-07
>
>
> To the IETF AVT working group and ITU SG16:
>
> --> Interested parties need to respond by end of day PST Monday 2/14 <--
>
> The following has come up during IESG discussion of the
> draft-ietf-avt-tones-06.txt document:
>
> > In section 3.11 there are two events (CRd and MRd) where the signals
> > are different for the initiator and the responder.
> > This implies that the entity doing the translation between
> audio and events
> > need to be aware of the higher layer roles of the communicating peers.
> > Is this a reasonable assumption?
>
> This appears to be a valid concern that we did not realize in the
> working group review of this document. One would want the gateway
> that is doing the translation from an event to a tone to not be
> required to know the higher layer roles.
>
> It would be possible to give two different codepoints to each of these
> events. I don't know if there has already been enough implementation
> of this protocol that this would cause a problem, and the purpose of
> this message is to find out. Given that the modem and fax tones were
> added fairly late in the development of the draft, I suspect is would
> not be a problem to add two codepoints in that section (32-47) without
> changing the other sections.
>
> The author (Henning Schulzrinne) agreed:
>
> > This is at least ambiguous, particularly for a "pass-through" gateway
> > that's pretty clueless as to call state. There are effectively four tone
> > sequences
> >
> > 1375/2002 followed by 1150
> > 1529/2225 followed by 1150
> > 1357/2002 followed by 1900
> > 1529/2225 followed by 1900
> >
> > My suggestion would be to split the Crd and Mrd into Crdi and Crdr for
> > the initiating and responding side. Same for the other pair.
>
> The draft has been revised to make this split, so the codepoints 41-49
> are now different. The revised draft has been submitted but is
> available in the meantime as:
>
> http://www.cs.columbia.edu/~hgs/rtp/drafts/draft-ietf-avt-tones-07.txt
> http://www.cs.columbia.edu/~hgs/rtp/drafts/draft-ietf-avt-tones-07.ps
>
> I believe that, subject to this change, the draft has been approved by
> the IESG. If there are no objections from the working group by the
> end of the day PST on Monday (2/14), then I will give our OK for the
> -07 draft be sent to the RFC editor. This is a very short response
> time, but our goal is to get the RFC number assigned before the end of
> the SG16 meeting on 2/18. To those at the SG16 meeting, please call
> this issue to the attention of interested parties that might not have
> seen this message.
> -- Steve Casner
>
>
>
______________________________________
Gunnar Hellström
Omnitor AB
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