Subject: RE: [Megaco] Call Progress Tones Generator Pkg

From: "Kevin Boyle" <[email-masked]>
Date: Thu, 13 Dec 2001 14:53:53 -0500

"Silence periods" is a bit misleading.  Any cadenced tone (such as busy) has
silent periods in it.  Several alternative call waiting tones are also
cadenced.  However, the 10 second interval is NOT part of the cadence.  The
switch alerts the phone by applying CWT tone.  Ten seconds later, the switch
re-alerts the phone by applying CWT tone.  It is two separate applications
of the same tone.

I believe that if the MGC wants to re-apply a tone, then it should do so,
and not depend on what might be a regional definition of "cycles".  There
are scenarios, defined by regional specs, where CWT tone shall only be
applied ONCE, due to interactions with other features, or line
configurations.  The same tone would be applied TWICE in the normal case.
It is outside the scope of Megaco to define the number of cycles for which a
tone should be applied.  There are constructs in the grammar to allow for
repeated cycling of a tone... or define the tone as a timeout tone.  If
there needs to be spaced application of the tone, such as with call wait,
then the MGC should be responsible for applying the tone at the appropriate
intervals, by reapplying the tone.

To sum up, cadence for a discrete tone is part of the definition of that
tone, and should be provisioned.  The number of cycles to apply should be
handled by making the tone a timeout tone, or by having the MGC reapply the
tone at appropriate intervals.

I do not see a problem with the text.

Kevin  

 -----Original Message-----
From: 	Terry L Anderson [mailto:[email-masked]] 
Sent:	Thursday, December 13, 2001 12:31 PM
To:	Megaco Mailing List
Subject:	[Megaco] Call Progress Tones Generator Pkg

 << File: Card for Terry L Anderson >> The Call Progress Tones Generator pkg
in Annex E.7 has little
information about the tones and simply points to ITU E.180 in the
procedures section.  This is sufficient for simple tones like dial tone,
but it leave a bit of ambiguity about more complex tones like Busy or
Call Waiting that have cadence.  Does the defined tone include silence
periods for the cadence or is it simply the tone for the "on" phase?

For example, the Call Waiting tone is "one or more cycles" of a tone
400-450 Hz with a cadence of
    on 300-500 ms, followed by silence for 8-10 sec, or
    on 100-200 ms, silence for 100-200 ms, on 100-200ms (total to be no
more than 500 ms), followed by silence for 8-10 sec

So does tone=cw simply give the 400-450 Hz tone leaving the cadence to
be controlled by MGC using duration and interleaved silence tones?  Or,
should the entire tone, choice of cadence and "one or more cycles" be
provisioned in MG as a signal and simply truncated if the specified
duration expires?

One complication is that the ITU intent is that voice be heard during
the 8-10 sec silence gap.  I am not sure how many MGs continue to
transfer media packets mid signal playout.  If not, they would not play
voice if the 8-10 s of silence were implemented as part of the signal.

It seems that the package should define whether tones include the
cadence and repetitions.

--

------------------------------------------------------------
Terry L Anderson              mailto:[email-masked]
Tel:908.582.7013   Fax:908.582.6729
Lucent Technologies/INS/Voice Over IP Access Networks
Rm 2B-121, 600 Mountain Av, Murray Hill, NJ 07974
http://its.lucent.com/~tla (Lucent internal) http://www.gti.net/tla

---

From: Terry L Anderson <[email-masked]>
Date: Fri, 14 Dec 2001 13:36:36 -0500

Unfortunately for the call waiting case, this distinction between
cadence and repetition interval is ambiguous.  E.180 uses the term
cadence when specifying the 8-10 sec of silence:

"and with a cadence (frequency sequence) as follows:
a) f on 300 to 500 ms, silence 8 to 10 s (f = 300 ms is preferable to
the longer tone since the ongoing conversation would be interrupted for
a briefer interval); or
b) f on 100 to 200 ms, silence 100 to 200 ms, f on 100 to 200 ms (the
total to be no more than 500 ms); 8 to 10 s silence."

So we agree that the '100-200 on, 100-200 off, 100-200 on' is cadence
but the sentence also states that the '300-500 ms on, 8-10 s off' is
"cadence".

Perhaps this is just a poor definition and we could accept the 8-10 sec
of silence as NOT part of the cadence and hence NOT part of cg/cw
signal.  But we still have a difficulty implementing the repetition in
H.248.

Method 1:
    Send cg/cw in a signal descriptor and set the signal completion
event to Notify when it completes.  MGC then sets a timer for 8-10 s
after receiving Notify and repeats cg/cw if desired.  The problem is
that I don't like MGC attempting "real time" control to meet a defined
standard.  Processing and message propogation delays make it difficult
to guarantee we meet the 8-10 window, although I admit this is long
enough and wide enough to reduce the  difficulty.  Other tones with
specified repeat intervals could be more difficult to meet.

Method 2:
    Send a SignalList containing cg/cw, silence, cg/cw.  The silence
could be a signal defined to have a length between 8 and 10 sec.  The
2nd cg/cw can still be cancelled, if desired, by sending a new
SignalDescriptor without KeepActive (probably empty).  The only
difficulty here is that there is no standard "silence" tone defined (or
any other way to introduce the delay in the SignalList).  Of course we
could add silence to cg or to a new package, but E.180 also suggests
that the tone is not intended to interfere with the existing
conversation.  This means that voice should be heard during the 8-10
sec.  So we really need a "transparent silence" tone.  It cannot be
implemented as other tones might be using a recorded file, say 8 sec of
0's.  Again harder but this would permit more careful regulation of the
8-10 sec interval.  But if this technique is to be interoperable, we
need to add such a standard tone.

Kevin Boyle wrote:

>
>
> "Silence periods" is a bit misleading.  Any cadenced tone (such as
> busy) has silent periods in it.  Several alternative call waiting
> tones are also cadenced.  However, the 10 second interval is NOT part
> of the cadence.  The switch alerts the phone by applying CWT tone.
> Ten seconds later, the switch re-alerts the phone by applying CWT
> tone.  It is two separate applications of the same tone.
>
> I believe that if the MGC wants to re-apply a tone, then it should do
> so, and not depend on what might be a regional definition of
> "cycles".  There are scenarios, defined by regional specs, where CWT
> tone shall only be applied ONCE, due to interactions with other
> features, or line configurations.  The same tone would be applied
> TWICE in the normal case.  It is outside the scope of Megaco to define
> the number of cycles for which a tone should be applied.  There are
> constructs in the grammar to allow for repeated cycling of a tone...
> or define the tone as a timeout tone.  If there needs to be spaced
> application of the tone, such as with call wait, then the MGC should
> be responsible for applying the tone at the appropriate intervals, by
> reapplying the tone.
>
> To sum up, cadence for a discrete tone is part of the definition of
> that tone, and should be provisioned.  The number of cycles to apply
> should be handled by making the tone a timeout tone, or by having the
> MGC reapply the tone at appropriate intervals.
>
>  << File: Card for Terry L Anderson >> The Call Progress Tones
> Generator pkg in Annex E.7 has little

--

---

From: Terry L Anderson <[email-masked]>
Date: Fri, 14 Dec 2001 13:36:36 -0500

Method 1:

Method 2:

--

---

From: Christian Groves <[email-masked]>
Date: Mon, 17 Dec 2001 11:09:36 +1100

G'Day Terry,

Can't you just send down Signal=CW,Type=ON/off? This will repeat the CW
tone with the provisioned cadence (silence period) until you turn it
off. I've always assumed that the silence period is provisioned with the
tone.

Regards, Christian

> > It seems that the package should define whether tones include the

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---

From: Christian Groves <[email-masked]>
Date: Mon, 17 Dec 2001 11:09:36 +1100

G'Day Terry,

Regards, Christian