Subject: [Megaco] class 4 and class 5 applications in H.248

From: "Pellegrino Jose Luis" <[email-masked]>
Date: Tue, 16 May 2006 12:59:30 -0300

Hi MeGaCo community,
 
I would like to ask you a question about class 4 and class 5 applications.
 
If I am not wrong, digit maps (point 7.1.14 of RFC 3525) and dd/ce have been developed to be used in class 5 application. In fact in my opinion we use digit map with residencial or access gateway, and not just in trunk gateway.
 
So the question is:
Is it possible to use dd/ce in trunk gateway in order to notify a MGC DTMF digits received by the MG during the conversation fase (I mean not during the stablishing period)? 
Or in the hand that feature requires to be implemented, an ad hoc modifications, I mean  It is not a natural use of dd/ce?
 
I will understand if you say that what I am asking for, sounds like strange. If you need more explanations  I can explain it in more detail. It is not related to the transport of DTMF from one MG to the other MG: in that case we use the RFC 2833 RTP mechanism.
 
Finally, in case what I am asking for is not possible or not recommended, what about of use of dd/std in class 4 applications.
 
Sorry for my bad english, and best regard in advance
 
José Luis Pellegrino
Telefónica de Argentina
_______________________________________________
Megaco mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/megaco

---

From: "Kevin Boyle" <[email-masked]>
Date: Wed, 17 May 2006 03:04:16 -0400

I disagree.  The MGC can decide to collect digits as appropriate on any
termination it wishes.

As is evident from the initial query, there are clearly usecases where
digit collection on a "trunk" interface is appropriate.  Therefore, the
assertion below that this is inappropriate is untrue.

Finally, the use of a completion event requires a DigitMap Descriptor.
If the intention is to collect single digits, then why incur the extra
overhead of a DigitMap when you can just use the individual digit
events?

Kevin 

-----Original Message-----
From: Yanssen, Rodrigo Duarte [mailto:[email-masked]] 
Sent: Tuesday, May 16, 2006 1:25 PM
To: Boyle, Kevin [NCRTP:3Z40:EXCH]; Pellegrino Jose Luis;
[email-masked]
Subject: RE: [Megaco] class 4 and class 5 applications in H.248

I think that the Access Gateways on market, treat a little quantity of
E1, normally only one STM-1, while a Virtual Trunk Gateway can control
up to 10 STM-1, so in my mind is not appropriate the MG proccess a lot
of DS0s with Digit Map, if these events had already completed in the
PSTN switch. 

Now, if you will use the event dd/ce sending digit by digit, you will
not use really this feature, so you are would using CE like STD. And we
can not mix Digits to Call Setup and Digits in_band that are using to
transport confidencials information like account bank and passwords,
that can be transported by in_band RFC 2833.

Regards

___________________________
Rodrigo Yanssen
Siemens - COM NSC FN E
Phone:  +55-11-3908-3527
Mobile: +55-19-9134-8168

-----Original Message-----
From: Kevin Boyle [mailto:[email-masked]]
Sent: terça-feira, 16 de maio de 2006 13:38
To: Pellegrino Jose Luis; [email-masked]
Subject: RE: [Megaco] class 4 and class 5 applications in H.248

The edd package in H.248.16 was designed for just the kind of
application you are suggesting here -- to collect digits mid-call.
Digit collection via a DigitMap in H.248 can occur at any time the MGC
chooses to do so by adding a completion event to the Events Descriptor
and setting a DigitMap Descriptor appropriately.
 
Kevin

________________________________

	From: Pellegrino Jose Luis [mailto:[email-masked]] 
	Sent: Tuesday, May 16, 2006 12:00 PM
	To: [email-masked]
	Subject: [Megaco] class 4 and class 5 applications in H.248

	Hi MeGaCo community,
	 
	I would like to ask you a question about class 4 and class 5
applications.
	 
	If I am not wrong, digit maps (point 7.1.14 of RFC 3525) and
dd/ce have been developed to be used in class 5 application. In fact in
my opinion we use digit map with residencial or access gateway, and not
just in trunk gateway.
	 
	So the question is:
	Is it possible to use dd/ce in trunk gateway in order to notify
a MGC DTMF digits received by the MG during the conversation fase (I
mean not during the stablishing period)? 
	Or in the hand that feature requires to be implemented, an ad
hoc modifications, I mean  It is not a natural use of dd/ce?
	 
	I will understand if you say that what I am asking for, sounds
like strange. If you need more explanations  I can explain it in more
detail. It is not related to the transport of DTMF from one MG to the
other MG: in that case we use the RFC 2833 RTP mechanism.
	 
	Finally, in case what I am asking for is not possible or not
recommended, what about of use of dd/std in class 4 applications.

	José Luis Pellegrino
	Telefónica de Argentina

---

From: "Kevin Boyle" <[email-masked]>
Date: Wed, 17 May 2006 15:44:24 -0400

These statements are completely contrary to the common understanding of
how H.248 works.

The MGC can set events of any kind at any time.  Call state is
irrelevant.  This includes using completion events with DigitMap
Descriptors.  I will note that I have seen this kind of usage in
deployed systems in the field.  So statements that something is
"inappropriate" in this regard sounds like a personal judgment, not a
fact of the network.

As for profiles, we have spent a lot of time and effort making profiles
workable within H.248 systems.  Their use is very appropriate, and it is
up to the network operator to ensure that the use of profiles does not
end up causing problems within the network.

Kevin 

-----Original Message-----
From: Yanssen, Rodrigo Duarte [mailto:[email-masked]] 
Sent: Wednesday, May 17, 2006 8:42 AM
To: [email-masked]
Cc: Boyle, Kevin [NCRTP:3Z40:EXCH]; [email-masked]; Pellegrino Jose
Luis

Ok, Srs. We have some diferents packeges for diferent application. But
we need to remember that our colleague Pelegrino asked to us about DTMF
in_band and out_band after established call.

My opinion is that the appropriated method is RFC2833 in_band, or DD/STD
for out_band digits because after established calls is not appropriate
to configure events to be completed (CE).

And I think that is not appopriate to have profiles on network, because
we would be create diferents cells in the same net.

Regards

Rodrigo Yanssen

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: quarta-feira, 17 de maio de 2006 04:26
To: Yanssen, Rodrigo Duarte
Cc: Kevin Boyle; [email-masked]; Pellegrino Jose Luis
Subject: RE: [Megaco] class 4 and class 5 applications in H.248

This view is too simplified in my opinion (because not considering the
different markets of legacy PSTN/ISDN networks).
You should at least distinguish ANSI and non-ANSI (like ETSI) markets.
The ANSI CLASS4 exchange is slightly different as the ETSI Transit
exchange
(TX) with regards the involvment in service control ("background is the
rather early de-regulation in ANSI markets 20 years ago with the two
business roles of a local operator and long distance operator").

If you then considering an NGN scenario with a replacement of the CLASS4
or
the TX by a H.248 Trunking Gateway, then you need two MG variants:

   (1) TMG_C4 (let's call it "CLASS4 Trunking Media Gateway")
   (2) TMG_TX (let's call it "Transit Trunking Media Gateway")

The 2nd one doesn't require DTMF support at the H.248 interface, -
neither
individual digits nor digitmaps -, from a replacement requirement. See
e.g.
ETSI ES 283 024, an H.248 Profile for ETSI TMG_TXs.

But the 1st one has typically that requirement. I also do agree to Kevin
that "DigitMap" support is needed for the TMG_C4 (e.g., the previous
CLASS4
could had an (INAP) interface to an IN SCP, which needs to be
continued).

Another reason is that the TMG_TX is typically considering only SS7
trunks
(like in ETSI TISPAN NGN R1), whereas there could be also CAS trunks
(like
SSR1, SSR2, SSR5). The TMG_C4 has typically to interface as well SSR1
trunks, which again may lead to the requirement of individual digits or
digitstring handling.

If you would made an attempt in comparing both TMGs by H.248 Profiles,
then
the H.248 TMG_TX Profile would be a subset of the H.248 TMG_C4 Profile.
And the TMG_C4 would need DigitMap support as outlined by Kevin.
This is related to the H.248 TDM Termination and has nothing to do with
the
RTP side.

My view, Albrecht

                      "Yanssen, Rodrigo

                      Duarte"                    To:      "Kevin Boyle"
<[email-masked]>, "Pellegrino Jose Luis"                  
                      <rodrigo.yanssen@s
<[email-masked]>, <[email-masked]>

                      iemens.com>                cc:

                                                 Subject: RE: [Megaco]
class 4 and class 5 applications in H.248                     
                      16.05.2006 14:24

I think that the Access Gateways on market, treat a little quantity of
E1,
normally only one STM-1, while a Virtual Trunk Gateway can control up to
10
STM-1, so in my mind is not appropriate the MG proccess a lot of DS0s
with
Digit Map, if these events had already completed in the PSTN switch.

Now, if you will use the event dd/ce sending digit by digit, you will
not
use really this feature, so you are would using CE like STD. And we can
not
mix Digits to Call Setup and Digits in_band that are using to transport
confidencials information like account bank and passwords, that can be
transported by in_band RFC 2833.

Regards

-----Original Message-----
From: Kevin Boyle [mailto:[email-masked]]
Sent: terça-feira, 16 de maio de 2006 13:38
To: Pellegrino Jose Luis; [email-masked]
Subject: RE: [Megaco] class 4 and class 5 applications in H.248

Kevin

             From: Pellegrino Jose Luis
[mailto:[email-masked]]

             Hi MeGaCo community,

             I would like to ask you a question about class 4 and class
5
applications.

             If I am not wrong, digit maps (point 7.1.14 of RFC 3525)
and
dd/ce have been developed to be used in class 5 application. In fact in
my opinion we use digit map with residencial or access gateway, and not
just in trunk gateway.

             So the question is:
             Is it possible to use dd/ce in trunk gateway in order to
notify
a MGC DTMF digits received by the MG during the conversation fase (I
mean not during the stablishing period)?
             Or in the hand that feature requires to be implemented, an
ad
hoc modifications, I mean  It is not a natural use of dd/ce?

             I will understand if you say that what I am asking for,
sounds
like strange. If you need more explanations  I can explain it in more
detail. It is not related to the transport of DTMF from one MG to the
other MG: in that case we use the RFC 2833 RTP mechanism.

             Finally, in case what I am asking for is not possible or
not
recommended, what about of use of dd/std in class 4 applications.

             José Luis Pellegrino
             Telefónica de Argentina

---

From: "Kevin Boyle" <[email-masked]>
Date: Wed, 17 May 2006 16:58:01 -0400

Profiles are specific to the MGC-MG control association.  Different MGs
are certainly allowed to use different profiles.  In fact, a particular
MG may use multiple profiles.

It would be up to the MGC to accept or reject the registration of MGs
depending upon the profiles implemented in the MGC.

Kevin 

-----Original Message-----
From: Yanssen, Rodrigo Duarte [mailto:[email-masked]] 
Sent: Wednesday, May 17, 2006 4:29 PM
To: Boyle, Kevin [NCRTP:3Z40:EXCH]; Jon Rowland;
[email-masked]
Cc: [email-masked]; Pellegrino Jose Luis
Subject: RE: [Megaco] class 4 and class 5 applications in H.248

Kevin,

Are there some problems to have one MGC controlling MGs with diferents
packages ? Eg.: Access Gateways and some Trunk Gateways using DD/CE and
others collecting digits via DD/STD ?

Could I have diferents profiles in MGC to control diferents MGs ?

Regards

-----Original Message-----
From: Kevin Boyle [mailto:[email-masked]]
Sent: quarta-feira, 17 de maio de 2006 17:00
To: Yanssen, Rodrigo Duarte; Jon Rowland; [email-masked]
Cc: [email-masked]; Pellegrino Jose Luis
Subject: RE: [Megaco] class 4 and class 5 applications in H.248

I think we all need to be careful here.  We are starting to dive into
what amount to implementation details.  If a particular implementation
needs DigitMaps where another doesn't, that is an indication that the
implementations are different not an indication that the protocol usage
is "appropriate" or "inappropriate".

H.248.1 does not give guidance on things like this for a reason: the
decision to do things in a particular way in the realm of call
processing is an implementation detail and is at the discretion of the
MGC.  As long as the messaging complies with the protocol as described
in H.248.1 and with the procedures defined in the packages in use, then
the call processing methodologies are secondary and not in scope for the
protocol to specify.

Certainly, there is no require to ever use DigitMaps -- even in
residential scenarios.  There are ways to collect digits that do not
require the use of a completion event and a DigitMap Descriptor.
However, the implementation decision is whether the advantages of using
a completion event and DigitMaps outweigh the disadvantages of doing
digit collection one digit at a time.  For different implementations,
this decision will differ.  It is not in the scope of the protocol or
this list to mandate that a particular implementation must or must not
use DigitMaps.

I will state for the record that there are a number of digit collection
scenarios in class 4 applications.  These may receive an advantage from
using DigitMaps in some implementations.  I have seen it done both ways
from highly reputable equipment in common use today from various
vendors.  In fact, I have seen the same implementation do single digit
collection using the discrete digit events and DigitMap collection using
a completion event depending upon the call state and expected collection
scenario.

Kevin 

-----Original Message-----
From: Yanssen, Rodrigo Duarte [mailto:[email-masked]]
Sent: Wednesday, May 17, 2006 3:00 PM
To: Jon Rowland; [email-masked]
Cc: [email-masked]; Pellegrino Jose Luis
Subject: RE: [Megaco] class 4 and class 5 applications in H.248

I agree you Jon, but our colleague told to us that the Digits is sending
out_band during the call established.

Because in this Net the Call Setup is make by ISUP and all digits are
sending within IAM message. 
So why I need of DigitMap ??

Best Regards 

-----Original Message-----
From: Jon Rowland [mailto:[email-masked]]
Sent: quarta-feira, 17 de maio de 2006 11:29
To: Yanssen, Rodrigo Duarte; [email-masked]
Cc: [email-masked]; Pellegrino Jose Luis
Subject: RE: [Megaco] class 4 and class 5 applications in H.248

A couple of points on this:

1) The distinction between RFC2833 and DD does not make sense. RFC2833
is a method for transmitting DTMF digits along the media path. DD is a
package for reporting events from the MG to the MGC. The MG can report
digit detection up to the MGC whether they are received in-band or
out-of-band. RFC2833 is not relevant to this discussion as I see it.

2) I see no reason why DD/CE is inappropriate in this case. The MGC is
free to request detection of either a digit map match or single digits
at any point. There are plenty of class 4 applications where this would
be appropriate to do on a trunk. 

Regards,
Jon.

-----Original Message-----
From: Yanssen, Rodrigo Duarte [mailto:[email-masked]]
Sent: 17 May 2006 13:42
To: [email-masked]
Cc: [email-masked]; Pellegrino Jose Luis
Subject: RE: [Megaco] class 4 and class 5 applications in H.248

Regards

Rodrigo Yanssen

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: quarta-feira, 17 de maio de 2006 04:26
To: Yanssen, Rodrigo Duarte
Cc: Kevin Boyle; [email-masked]; Pellegrino Jose Luis
Subject: RE: [Megaco] class 4 and class 5 applications in H.248

If you then considering an NGN scenario with a replacement of the CLASS4
or the TX by a H.248 Trunking Gateway, then you need two MG variants:

The 2nd one doesn't require DTMF support at the H.248 interface, -
neither individual digits nor digitmaps -, from a replacement
requirement. See e.g.
ETSI ES 283 024, an H.248 Profile for ETSI TMG_TXs.

But the 1st one has typically that requirement. I also do agree to Kevin
that "DigitMap" support is needed for the TMG_C4 (e.g., the previous
CLASS4 could had an (INAP) interface to an IN SCP, which needs to be
continued).

Another reason is that the TMG_TX is typically considering only SS7
trunks (like in ETSI TISPAN NGN R1), whereas there could be also CAS
trunks (like SSR1, SSR2, SSR5). The TMG_C4 has typically to interface as
well SSR1 trunks, which again may lead to the requirement of individual
digits or digitstring handling.

If you would made an attempt in comparing both TMGs by H.248 Profiles,
then the H.248 TMG_TX Profile would be a subset of the H.248 TMG_C4
Profile.
And the TMG_C4 would need DigitMap support as outlined by Kevin.
This is related to the H.248 TDM Termination and has nothing to do with
the RTP side.

My view, Albrecht

                      "Yanssen, Rodrigo

                      iemens.com>                cc:

                                                 Subject: RE: [Megaco]

Regards

-----Original Message-----
From: Kevin Boyle [mailto:[email-masked]]
Sent: terça-feira, 16 de maio de 2006 13:38
To: Pellegrino Jose Luis; [email-masked]
Subject: RE: [Megaco] class 4 and class 5 applications in H.248

Kevin

             Hi MeGaCo community,

5 applications.

             If I am not wrong, digit maps (point 7.1.14 of RFC 3525)
and dd/ce have been developed to be used in class 5 application. In fact
in my opinion we use digit map with residencial or access gateway, and
not just in trunk gateway.

             So the question is:
             Is it possible to use dd/ce in trunk gateway in order to
notify a MGC DTMF digits received by the MG during the conversation fase
(I mean not during the stablishing period)?
             Or in the hand that feature requires to be implemented, an
ad hoc modifications, I mean  It is not a natural use of dd/ce?

             I will understand if you say that what I am asking for,
sounds like strange. If you need more explanations  I can explain it in
more detail. It is not related to the transport of DTMF from one MG to
the other MG: in that case we use the RFC 2833 RTP mechanism.

             Finally, in case what I am asking for is not possible or
not recommended, what about of use of dd/std in class 4 applications.

             José Luis Pellegrino
             Telefónica de Argentina