Subject: [Megaco] Problem using FLASH (fl) event

From: "Mihai Dobre" <[email-masked]>
Date: Thu, 22 Feb 2007 20:26:51 +0200

Hello Everybody,

My name is Mihai Dobre and I work as telecom engineer. During last months
the company where I work implements a VoIP system using one MGC and one
large MGW (672 subscribers). I posses basic knowledge of MEGACO v1 protocol
which help me to implement this VoIP system but now I has a problem that is
over my knowledge and I kindly request your support.

Problem description:
When a subscriber want to use one of the services: Call Waiting, Triparty or
Conferece which use the FLASH key the MGW sends to MGC the event al/on
instead of al/fl. I've discuss with the provider of MGW and after I send
traces to them they claim that is the fault because MGC does not request on
MGW this specific event - al/fl.
My question if is mandatory that MGC to send all the supported events
(example: {al/on, al/of, al/fl, al/ri.....and so on} ) to MGW in order to
provide full functionality of MGW.
My opinion is that the MGW should send in NOTIFY command the new observed
event and if is supported by MGC then proceed with the second dial tone.

Thanks in advance.

Best regards
Mihai DOBRE
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Megaco mailing list
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https://www1.ietf.org/mailman/listinfo/megaco

---

From: "Tom-PT Taylor" <[email-masked]>
Date: Thu, 22 Feb 2007 13:45:23 -0500

The MGC has to request the events it wants reported. The others will not 
be reported. One thing the MGC can do, though, is request al/*, that is, 
all events in the al package.

Mihai Dobre wrote:
> Hello Everybody,
> 
> My name is Mihai Dobre and I work as telecom engineer. During last months the company where I work implements a VoIP system using one MGC and one large MGW (672 subscribers). I posses basic knowledge of MEGACO v1 protocol which help me to implement this VoIP system but now I has a problem that is over my knowledge and I kindly request your support. 
> 
> Problem description:
> When a subscriber want to use one of the services: Call Waiting, Triparty or Conferece which use the FLASH key the MGW sends to MGC the event al/on instead of al/fl. I've discuss with the provider of MGW and after I send traces to them they claim that is the fault because MGC does not request on MGW this specific event - al/fl. 
> My question if is mandatory that MGC to send all the supported events (example: {al/on, al/of, al/fl, al/ri.....and so on} ) to MGW in order to provide full functionality of MGW.
> My opinion is that the MGW should send in NOTIFY command the new observed event and if is supported by MGC then proceed with the second dial tone.
> 
> Thanks in advance.
> 
> Best regards
> Mihai DOBRE
> 
>

---

From: "Mihai Dobre" <[email-masked]>
Date: Thu, 22 Feb 2007 21:31:27 +0200

Hello,

Thank you for your quick answer.

Ok, the way that MGC deal with the FLASH event is incorrect because does not
armed the MGW to observe this specific event or all events; but why MGW does
not report error?

Best regards,
Mihai DOBRE

On 2/22/07, Tom-PT Taylor <[email-masked]> wrote:
> > My name is Mihai Dobre and I work as telecom engineer. During last
> months the company where I work implements a VoIP system using one MGC and
> one large MGW (672 subscribers). I posses basic knowledge of MEGACO v1
> protocol which help me to implement this VoIP system but now I has a problem
> that is over my knowledge and I kindly request your support.
> >
> > Problem description:
> > When a subscriber want to use one of the services: Call Waiting,
> Triparty or Conferece which use the FLASH key the MGW sends to MGC the event
> al/on instead of al/fl. I've discuss with the provider of MGW and after I
> send traces to them they claim that is the fault because MGC does not
> request on MGW this specific event - al/fl.
> > My opinion is that the MGW should send in NOTIFY command the new
> observed event and if is supported by MGC then proceed with the second dial
> tone.
> >
> > Thanks in advance.
> >
> > Best regards
> > Mihai DOBRE
> >
> >
>

---

From: "Wglastonio Sousa" <[email-masked]>
Date: Thu, 22 Feb 2007 17:35:21 -0200

Hello,

I include bellow a related citation from Rec H.248.1:

-------------------------------------------------
*7 Commands*

*The protocol provides commands for manipulating the logical entities of the
protocol connection model, contexts and terminations. Commands provide
control at the finest level of granularity supported by the protocol. For
example, commands exist to add terminations to a context, modify
terminations, subtract terminations from a context, and audit properties of
contexts or terminations. Commands provide for complete control of the
properties of contexts and terminations. This includes specifying which
events a termination is to report, which signals/actions are to be applied
to a termination and specifying the topology of a context (who hears/sees
whom).*
-------------------------------------------------

If MGW sends a NOTIFY command to MGC for any new observed event, it could to
cause a avalanche on the MGC.

Regards,

Wglastonio.

---

From: "Tom-PT Taylor" <[email-masked]>
Date: Thu, 22 Feb 2007 14:56:36 -0500

It is not an error for the MGC to fail to arm all possible events. Some 
events are not relevant in a particular situation. Or the MGC 
implementation does not handle some events. That may or may not mean 
loss of functionality.

As one example, the MGC is generally not going to be interested in the 
g/sc (signal completion) event -- only in specific circumstances.

If al/fl is not enabled, I assume the MGC is seeing al/on followed very 
quickly by al/off, unless it happens that the latter is not enabled.

Mihai Dobre wrote:
> Ok, the way that MGC deal with the FLASH event is incorrect because does not armed the MGW to observe this specific event or all events; but why MGW does not report error?
> 
> Best regards,
> Mihai DOBRE
> 
>

---

From: "Kevin Boyle" <[email-masked]>
Date: Thu, 22 Feb 2007 15:07:00 -0500

Note that the MGC may be intentionally trying to prevent the user from
flashing.  This is also a possibility.  It is up to the call processing
code in the MGC to decide whether or not to arm and accept events based
upon the functionality it contains and wishes to provide to the MG.

Kevin 

-----Original Message-----
From: Taylor, Tom-PT (CAR:AR00) 
Sent: Thursday, February 22, 2007 2:57 PM
To: Mihai Dobre
Cc: [email-masked]
Subject: Re: [Megaco] Problem using FLASH (fl) event

Mihai Dobre wrote:
> Ok, the way that MGC deal with the FLASH event is incorrect because
does not armed the MGW to observe this specific event or all events; but
why MGW does not report error?
> 	> My name is Mihai Dobre and I work as telecom engineer. During
last months the company where I work implements a VoIP system using one
MGC and one large MGW (672 subscribers). I posses basic knowledge of
MEGACO v1 protocol which help me to implement this VoIP system but now I
has a problem that is over my knowledge and I kindly request your
support. 
> 	>
> 	> Problem description:
> 	> When a subscriber want to use one of the services: Call
Waiting, Triparty or Conferece which use the FLASH key the MGW sends to
MGC the event al/on instead of al/fl. I've discuss with the provider of
MGW and after I send traces to them they claim that is the fault because
MGC does not request on MGW this specific event - al/fl. 
> 	> My question if is mandatory that MGC to send all the supported
events (example: {al/on, al/of, al/fl, al/ri.....and so on} ) to MGW in
order to provide full functionality of MGW.
> 	> My opinion is that the MGW should send in NOTIFY command the
new observed event and if is supported by MGC then proceed with the
second dial tone.

---

From: "Mihai Dobre" <[email-masked]>
Date: Mon, 26 Feb 2007 15:31:36 +0200

Dear All,

First of all thanks for your quick answers at my problem.

Now the MGC inform and arm MGW with FLASH event as you can see in the below
message:

MEGACO/1 [10.10.0.10]:2944
T=372884576{C=-{MF=al/1/2/27{E=370114304{dd/ce{DigitMap=dmap1},al/on{strict=exact},al/of{strict=exact},al/fl},SG{cg/dt},
DM=dmap1{([2-8]xxxxx|13xxxxxxxxx|0xxxxxxxx|9xxxx|1[0124-9]x|E|F|x.F|[0-9].L)}}}

But another problem apear when a phone device with mechanical dial rotary
which normally use PULSE is connected at MGW. So, when a phone like this
(which use PULSE) try to dial a phone number that contain the digit "1", MGW
sends a NOTIFY command with observed event FLASH:

MEGACO/1 [10.10.0.58]:2944
Transaction=20397{Context=-{Notify=al/1/2/27{ObservedEvents=370114304{20070223T14360940:al/fl}}}}

I know that FLASH can be substitute with a short press on switch
on-hook/off-hook and also the digit "1" when PULSE is use it's similar with
a short on-hook/off-hook. In this way a subscriber can never dial a number
that contain the digit "1" from a PULSE phone.

My question is if is normal that MGW to observe the event FLASH when waits
for dialed digits or if is another way to avoid this odd situation.

Best regards,
Mihai DOBRE

---

From: "Wglastonio Sousa" <[email-masked]>
Date: Mon, 26 Feb 2007 13:59:23 -0300

Hello Mihai,

The pulse interval for "digit pulse" and "flash pulse" are different.
MGW should identify this difference, for this two events.

For instance (Brazil):

   - digit pulse ~ 10 ms (with an interval = 100ms between them);
   - flash pulse > 100ms;

Note: These pulse intervals depends on the country, but there are a band
between them to assure the identification of events.

Regards,

Wglastonio.

2007/2/26, Mihai Dobre <[email-masked]>:
> Now the MGC inform and arm MGW with FLASH event as you can see in the
> below message:
>
> MEGACO/1 [ 10.10.0.10]:2944
> > > On 2/22/07, Tom-PT Taylor < [email-masked]> wrote:
> > >