Subject: RE: [Megaco] Signals played on a TDM termination in H.248

From: "Anant Kumar \(anant\)" <[email-masked]>
Date: Thu, 25 Aug 2005 16:21:46 -0700

> 
> [ANANT] I am not suggesting that this is accomplished using a MOVE. 
> This would be a SUBTRACT operation as you correctly point out. My 
> contention is that this is in effect a move from a non-NULL to a NULL
context.
> hence, the question below. 
> 
> It seems that when a termination moves from a non-NULL to NULL 
> termination (SUBTRACT) the signal is halted. However, when it moves 
> from a NULL - non-NULL context (ADD) or from a non-NULL to a non-NULL 
> context (MOVE), the signal is unaffected. Is that the intent? If so, I

> would like to understand better the rationale behind this.
>
[PTT] The reason we made that decision was to provide predictable
behaviour for terminations in NULL context.  We thought that if the MGC
did a SUBTRACT and existing state persisted, this would be a mental
hazard for designers.  They might forget to reset that state to
something appropriate to the NULL context in their MGC code.

I should say that this was not a universally-welcomed decision, though I
recall only Brian Rosen protesting it.

[ANANT] But you could play a signal on a termination without adding it
to a context. So, not all terms in the NULL context are necessarily in
the default state.

In the xGCP world, the MGC needs to explicitly clear signals and events,
if it so desires. They are not implicitly cleared upon DLCX.

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From: "Tom-PT Taylor" <[email-masked]>
Date: Thu, 25 Aug 2005 21:58:08 -0400

Basically it was a judgement call, but there it is.  Megaco/H.248 is not 
xGCP, even though it inherited a lot from it.

Anant Kumar (anant) wrote:
...