Subject: RE: [Megaco] interpretation of H.248.23 andisp packageandthedwa / data signals

From: "Kevin Boyle" <[email-masked]>
Date: Thu, 28 Apr 2005 10:52:58 -0400

Comments inline. [KJBII]
 
Kevin

  _____  

From: [email-masked] [mailto:[email-masked]] On Behalf Of
Dal Chohan
Sent: Thursday, April 28, 2005 10:12 AM
To: 'Wayne Cutler'
Cc: [email-masked]; [email-masked]; [email-masked]
Subject: RE: [Megaco] interpretation of H.248.23 andisp packageandthedwa
/data signals

Hi Wayne,

>From reading the e-mails there appear to be two different approaches for
providing "On-Hook" display associated with ringing using the H.248 "andisp"
package. 

One approach assumes that the TAS signal is determined/provisioned within
the MGC (i.e. andisp/data) and the other approach that assumes the TAS
signal is determined/provisioned in the MG (i.e. andisp/dwa).
[KJBII] While there are two approaches to the transfer of the data using the
andisp package, they are not the approaches you describe.  One approach is
if the data transfer is associated with alerting (dwa) and the other is if
the data transfer is not associated with ringing (data).  The reason why the
TAS can be specified for andisp/data is that some features allow multiple
FSK transfers without the use of a new TAS for each FSK message.  The data
signal, therefore, allows the suppression of the TAS for those features.

I can understand why a number of implementations have adopted the former
approach, because it provides a single and consistent mechanism for
delivering "On-hook" display "during ringing", "prior to ringing" and "not
associated with ringing". Moreover it means that a single signal
"andisp/data" can be used for delivering all variants of the "On-Hook" and
even the "Off-Hook" display service.
[KJBII] How many is "a number"?  The design intent of the package does not
contemplate the use of the data signal with alerting.  The timing involved
is too tight for the successful use of the data signal without the
incorporation of undocumented kludges to the protocol, such as assumption of
timing associated with SignalLists -- or worse, playtone. This is especially
true of offhook FSK delivery.

If the latter method is used, then it means the two different signals must
be used. The signal "andisp/dwa" for "On-Hook" display associated with
ringing. The signal "andisp/data" for "On-Hook" display not associated with
ringing. Also the TAS signal for the "andisp/dwa" case is
determined/provisioned within the MG, while for the "andisp/data" case the
TAS is determined/provisioned within the MGC.  This does mean things are
modelled differently for the two cases and this does seem to be an odd
approach and incorrect from a service modeling and provisioning perspective.
[KJBII] This is, in fact, how the package was designed.  It is entirely
logical to break them up into two different signals.  You seem to be
ignoring the fact that the dwa signal carries a pattern parameter, which
allows the specification of alerting as part of the signal as well.  There
is no such parameter for andisp/data -- because there is no alerting pattern
to specify! I do not see how this is odd at all.  In fact, what I find odd
is the misinterpretation involved here.  The procedures section describes a
number of usecases in detail. 

We can either try to mandate that "andisp/dwa" is used for "On-Hook" display
prior to and during ringing, but there appears to be a lot of benefits and
mileage in allowing "andisp/data" to be used for "On-Hook" display prior to
ringing, during ringing and not associated with ringing- especially since a
number of implementations have already adopted this approach. 

[KJBII] I believe the package should be used as it was designed --
andisp/dwa for data transfer associated with alerting, and andisp/data for
data transfer not associated with alerting.  Use of data for alerting
scenarios will lead to timing issues and failures.

 

Regards,

Dal.

 

  _____  

From: [email-masked] [mailto:[email-masked]] On Behalf Of
Wayne Cutler
Sent: 28 April 2005 10:06
To: [email-masked]
Cc: [email-masked]; [email-masked]; [email-masked]
Subject: RE: [Megaco] interpretation of H.248.23 andisp package andthedwa
/data signals

Hi Kevin, 

ETSI FSK delivery is described in ETSI EN 300 659 which has a section (6.1)
called "Data Transmission Associated with Ringing" which is then further
split into 2 sub-sections, namely "Data Transmission during Ringing" (6.1.1)
and "Data Transmission Prior to Ringing" (6.1.2). 

Interestingly, the trasnmission that uses a TAS of RP is regarded as "prior
to ringing" since the timings are different to the splash of ringing that is
used 
for the "during ringing" scenario. 

Therefore, the andisp dwa & data signals align nicely with the ETSI split
and more than one company has interpreted the standard in this way and
progressed to implementation. I would  disagree with your assertion about
the procedures "clearly stating" this distinction. In fact, the cited UK
example is incorrect since there are two methods used in the UK, namely the
"BT method" which is prior to ringing (and uses a TAS or LR followed by
DT-AS) and the "Bellocore" method used by Cable Operators (that uses a TAS
of RP). 

I think it's a bit late to try and claim that the H248.23 words "during
alerting" means "associated with alerting" - especially given the wording of
the EN. 

Regards, 
Wayne 

"Kevin Boyle" <[email-masked]> 

27/04/2005 17:52 

        To:        Wayne Cutler <[email-masked]>,
[email-masked] 
        cc:        [email-masked], [email-masked],
[email-masked] 
        Subject:        RE: [Megaco] interpretation of H.248.23 andisp
package and thedwa        /data signals

Your interpretation is incorrect.  The dwa signal is designed to perform
data delivery associated with ANY alerting, whether prior to or during
ringing.  This is clearly stated in the procedures section of the document. 

Kevin 

-----Original Message----- 
From: [email-masked] [ <mailto:[email-masked]>
mailto:[email-masked]] On Behalf Of Wayne Cutler 
Sent: Tuesday, April 26, 2005 5:45 AM 
To: [email-masked] 
Cc: [email-masked]; [email-masked]; [email-masked] 
Subject: Re: [Megaco] interpretation of H.248.23 andisp package and
thedwa/data signals 

>Question 1: 

>The description of the display with alerting signal in H.248.23 has the 
following text: 

>"Sends the display information to the CPE. This signal indicates that 
>the 
data must be applied during alerting ? either power ringing, or call
waiting. >Therefore, this signal implies alerting, which will be
appropriately applied to the CPE by the gateway, based upon the on
hook/off-hook status of the >line." 

>The ETSI specification, EN 300 659-1, On-Hook Data Transmission, 
>defines 
the following data transmission methods: 
>1. prior to ringing (including TAS equal to Ringing Pulse-Alert 
>Singal), 2. during ringing (ie between the first and second ringing 
>pattern) 

>Which signals defined in the andisp package should be used to support 
>the 
two methods because it is not clear from the andisp package descrition for
dwa >signal can be applied for method 1? 

>Question 2: 

>Additionally it would be useful to find out what MG and MGC vendors 
>have 
implemented for methods 1 and 2. 

Hi Jan, 

For question 1, we'd read h248.23 as meaning that andisp/dwa should be used
for option 2 (during ringing) and andisp/data for option 1 (prior to
ringing). 

In terms of question 2, this is what the Marconi CA & MSAN has implemented. 

Regards, 
Wayne 

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---

From: "Dal Chohan" <[email-masked]>
Date: Thu, 28 Apr 2005 17:23:19 +0100

Comments in-line.

I don't understand why the use of a signal list containing an "andisp/data"
and a ringing signal would lead to timing issues for display associated with
ringing?

We have successfully implemented and demonstrated the "caller display"
service during and prior to "ringing" using the "andisp/data" mechanism on
our MG and MGC.

Regards,

Dal.

  _____  

From: Kevin Boyle [mailto:[email-masked]] 
Sent: 28 April 2005 15:53
To: Dal Chohan; 'Wayne Cutler'
Cc: [email-masked]; [email-masked]
Subject: RE: [Megaco] interpretation of H.248.23 andisp packageandthedwa
/data signals

Comments inline. [KJBII]

Kevin

  _____  

Hi Wayne,

[Dal] - The ability to use different TAS signals is also useful for
supporting the different range of services ranging from subscriber services
such as display services and for telemetry applications.

[Dal] From the e-mail exchange it looks like at least Alcatel, Marconi and
Fujitsu have implementations that use "andisp/data" for display services
associated with ringing. As stated earlier I don't understand what the
timing issues are - Which timers are you referring to?

[Dal] - The fact the "dwa" carries a pattern parameter is neither here or
there - the pattern parameter would be part of the ring signal which would
be contained in the Signal List. The fact that two different mechanisms are
used is "odd", because if for example you use a "ring pulse alert" signal
for display prior to ringing and a "ring pulse alert" signal not associated
with ringing, then why should this need to different signals. Especially
since the same set of analogue signals are generated by the MG over the
analogue interface for both these methods.

[Dal] - I don't understand what the timing issues are? With the andisp/data
the MG runs timers after the TAS and after the FSK signal - How is this
timing any different to the "display associated with ringing".

The bottom line is that you have cut your cloth using two different signals
"dwa" and "data" in the "andisp" package, but using just one signal has its
merits, does work successfully and is not illegal. 

 

Regards,

Dal.

 

  _____  

Hi Kevin, 

Regards, 
Wayne 

27/04/2005 17:52 

Kevin 

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

Hi Jan, 

Regards, 
Wayne