Subject: RE: [Megaco] Comfort Tone?

From: "Blatherwick, Peter" <[email-masked]>
Date: Tue, 20 Nov 2001 20:30:34 -0500

MY comfort tone is really really loud clashing guitars...   Oh, sorry, you were probably looking for a standards kind of definition.  (Sorry, could not resist.  ;-)   

Seriously, what "comfort tone" do you mean?  Do you mean the noise intentionally put in by codecs to mask the uncomfortable sound of real silence, do you mean those little tones on hold to tell you the call is still alive?  What specific reference are you trying to resolve?  

-- Peter

-----Original Message-----
From: Paul Long [mailto:[email-masked]]
Sent: November 20, 2001 19:27
To: [email-masked]
Subject: [Megaco] Comfort Tone?

Anyone know what the aural characteristics of comfort tone are? IOW, what
the heck does it sound like? I know this could vary from region to region,
but I can't recall ever hearing it or seeing a description of it.

Paul Long
ipDialog, Inc.

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---

From: "Paul Long" <[email-masked]>
Date: Wed, 21 Nov 2001 10:06:51 -0600

Peter,

Ha ha. :-|

I mean, "comfort tone" as in RFC 2833, E.182, and various Megaco/MGCP
packages and NOT codec "comfort noise." The following is taken from E.182.

            (3) that when a subscriber should wait for a network reaction,
       no  tones  or  announcement should be given. This condition applies
       during, e.g., dial-tone delay and post-dialling  delay.  Exception-
       ally  when  a  post-dialling  delay  on  an  outgoing international
       automatic call occurs that is likely to cause a subscriber to aban-
       don  the call, an appropriate announcement or a comfort tone may be
       used if it has been shown to reduce premature abandonment;

Someone replied to me privately with this URL:
http://www.hellosoft.com/products/hellovoice/cpt.html  It says that comfort
tone varies from system to system, although they use a continuous 480Hz tone
(I wonder what waveform, though). So there may not be a standard for this
tone, unlike dialtone and busy.

Paul

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On Behalf Of
Blatherwick, Peter
Sent: Tuesday, November 20, 2001 7:31 PM
To: 'Paul Long'; [email-masked]
Subject: RE: [Megaco] Comfort Tone?

MY comfort tone is really really loud clashing guitars...   Oh, sorry, you
were probably looking for a standards kind of definition.  (Sorry, could not
resist.  ;-)

Seriously, what "comfort tone" do you mean?  Do you mean the noise
intentionally put in by codecs to mask the uncomfortable sound of real
silence, do you mean those little tones on hold to tell you the call is
still alive?  What specific reference are you trying to resolve?

-- Peter

-----Original Message-----
From: Paul Long [mailto:[email-masked]]
Sent: November 20, 2001 19:27
To: [email-masked]
Subject: [Megaco] Comfort Tone?

Paul Long
ipDialog, Inc.

---

From: "Paul Long" <[email-masked]>
Date: Wed, 21 Nov 2001 10:06:51 -0600

Peter,

Ha ha. :-|

Paul

-----Original Message-----

-- Peter

-----Original Message-----
From: Paul Long [mailto:[email-masked]]
Sent: November 20, 2001 19:27
To: [email-masked]
Subject: [Megaco] Comfort Tone?

Paul Long
ipDialog, Inc.

---

From: "Vance Shipley" <[email-masked]>
Date: Wed, 21 Nov 2001 13:22:13 -0500

Paul Long writes:
> It says that comfort tone varies from system to system, although they 
> use a continuous 480Hz tone (I wonder what waveform, though). So there 
> may not be a standard for this tone, unlike dialtone and busy.

As someone who spends a lot of time referencing E.180 "Various Tones used
in National Networks" I would dispute the statement that there was a
standard for dialtone and busy.  We make call progress analysis software
for answer supervision detection.  We find some pretty bizarre tones used
in national networks.

E.180 is an annex to the operational bulletin and is really just a 
collection of statements provided by national operators.  It isn't by
any means definitive, or even remotely accurate, unfortunately.

	-Vance

Vance Shipley
Motivity Telecom Inc.
+1 519 579 5816

---

From: "Vance Shipley" <[email-masked]>
Date: Wed, 21 Nov 2001 13:22:13 -0500

-Vance

Vance Shipley
Motivity Telecom Inc.
+1 519 579 5816

---

From: "Paul Long" <[email-masked]>
Date: Wed, 21 Nov 2001 13:14:26 -0600

Vance,

Okay, point taken. However, from my personal experience most dial tones,
busy, and special information tones in the States sound the same. I'm
guessing that they are using E.180.

Regarding comfort tone, is the continuous 480Hz tone described on that web
site typical or does literally everybody do it differently? Actually, the
best indicator to a user that a call is proceeding may be to just randomly
play a few clicks and pops. :-) I know that when the line goes completely
dead that the call has been dropped.

Paul Long
ipDialog, Inc.

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On Behalf Of
Vance Shipley
Sent: Wednesday, November 21, 2001 12:22 PM
To: Paul Long
Cc: [email-masked]
Subject: RE: [Megaco] Comfort Tone?

	-Vance

Vance Shipley
Motivity Telecom Inc.
+1 519 579 5816

---

From: "Paul Long" <[email-masked]>
Date: Wed, 21 Nov 2001 13:14:26 -0600

Vance,

Paul Long
ipDialog, Inc.

-----Original Message-----

	-Vance

Vance Shipley
Motivity Telecom Inc.
+1 519 579 5816