Subject: [AVT] rfc2833 - general questions

From: tk <[email-masked]>
Date: Wed, 12 Oct 2005 09:45:15 +0800

dear all,
 thanks Tom Taylor for answers to the previous email.
i have a few general questions regarding this rfc.
 1) uses of standard subscriber line tones (eg events 64-66)
This is a newbie question. if one uses
a signalling protocol such as SIP, will there be a need for
these line events and the likes? (I understand that only events 0-15
are required for compliance to the RFC). Could someone kindly point
me to some resources stating what tones are used for various
countries. I have tried to search but in vain.
 2) flash event. why is this a dtmf event? and what is the tone for
flash? i presume flash is normally signalled out-of-band from the
dtmf stream.
 thanks in advance,
tk
_______________________________________________
Audio/Video Transport Working Group
[email-masked]
https://www1.ietf.org/mailman/listinfo/avt

---

From: "Tom-PT Taylor" <[email-masked]>
Date: Wed, 12 Oct 2005 09:47:59 -0400

Hi.  Note first of all that RFC 2833 has been radically restructured and 
is being replaced by three documents, two of which are currently in WG 
Last Call:

http://www.ietf.org/internet-drafts/draft-ietf-avt-rfc2833bis-10.txt
http://www.ietf.org/internet-drafts/draft-ietf-avt-rfc2833bisdata-04.txt

I see the CAS events document has expired.  I'll recycle it in 
preparation (I hope) for WGLC as soon as I have time.

The line events other than DTMF tones are not currently being propagated 
to the new documents, because there is no evidence they are actually 
implemented by anyone.  It's always possible to create a document for 
them if it turns out they are needed.

Detailed answers below.

> countries. I have tried to search but in vain.

[PTT] Clearly the only need for such events would be for interworking 
with legacy lines.  Even there, it would be a matter of remote equipment 
(located near the subscriber) exchanging line signalling with equipment 
co-located with the equivalent of a local switching office.  Perhaps a 
replacement for GR-303, for instance.

Here is a reference for local use of tones that I included in the -04 
version of rfc2833bis before the document was split:

  International Telecommunication Union, "Various tones used in
  national networks", Recommendation Supplement 2 to
  Recommendation E.180, ITU-T, Geneva, Switzerland, Jan. 1994.
  This publication has now been replaced by a list periodically
  updated and available through the "International Numbering
  Resources" link on the ITU-T home page.  The latest version
  (dated Feb. 2003) appears as an annex to ITU-T Operational
  Bulletin 781.  While a price is posted for the Operational
  Bulletin, the list itself is available at no charge through
  the "Lists annexed..." link on the Operational Bulletin page.

> flash? i presume flash is normally signalled out-of-band from the

[PTT]  That was one of the earliest things that caught my eye when I 
started the work of rewriting RFC 2833.  Flash has been removed from the 
set of DTMF events, which are still documented in the base document, 
rfc2833bis.

>  thanks in advance,
> tk
> 
> 
> 
> ------------------------------------------------------------------------
>

---

From: [email-masked]
Date: Wed, 12 Oct 2005 17:53:17 +0200

Hello,

we currently implement  the inband DTMF as described in the RFC2833. Do we 
have to consider that the current RFC2833 specification is now obsolete 
and that this new RFC2833bis draft becomes the reference.

Thanks in advance for your answer.

Regards,

Yanncik STEPHAN

"Tom-PT Taylor" <[email-masked]>
Sent by: [email-masked]
12/10/2005 15:47
 
        To:     tk <[email-masked]>
        cc:     [email-masked]
        Subject:        Re: [AVT] rfc2833 - general questions

Detailed answers below.

---

From: "Tom-PT Taylor" <[email-masked]>
Date: Wed, 12 Oct 2005 14:21:13 -0400

Technically, not until the new publication is published as an RFC. 
However, it is backward compatible, and (assuming no one finds any 
problems) contains detailed information not present in the original 
document.  Thus it wouldn't hurt to build to it.