Subject: Re: digit map questions

From: Michael Brown <[email-masked]>
Date: Tue, 18 Jan 2000 16:22:07 -0500

Sorry for the extreme delay in this response to the questions. I guess I
must have overlooked this when it was first posted, but was asked
recently by one of my colleagues if I would take a stab at answers since
no one else had done so.

Comments inline.

"John A. Voelker" wrote:

> A colleague asked me to place on the list some questions he had concerning digit
> maps (from  S7.1.13 of the h.248v12 draft):  Would appreciate any
> clarifications.
>
> John
> ===========================================================
>
> 1. What is the correct operational model for the inter-digit timing
> mechanism?
>   - One timer for the entire digitmap whose timeout interval is changed
> by an L or an S in the digitmap, or
>   - Two timers that are reset following each digit and generate an "L"
> or "S" when they expire?
> The wording of rules 2 and 3 seems to imply the first, but then I'm
> unclear on the use of "L" and "S" in the digitmap. Also, are there
> situations where the conditions of both rules are true?

<MB> Definitely the intent is the first model. I don't believe that
there is a
condition where both rules can apply.

>
> 2. This question assumes the first of the models listed above.  If
> several viable alternatives specify different inter-digit timeout
> values, which one is used?  For example, a "4" is received when the
> digitmap is:
>     { [2-9]Lxxxxxx | [3-8]Sxxxxxx }

<MB> This example digit map is non deterministic and therefore IMO not
legal.
However, if this map was used I believe the intended approach would be
that the
digit map patterns would be checked from left to right and therefore the
first
pattern and timer would apply.

>
> 3. What does the "." character indicate?  It appears to perform the same
> role as "*" in regular expressions, i.e. that it means 0 or more of the
> immediately preceding digitPosition.

<MB> The "." means collect and continue collecting until specified
timeout  or other
end of dialing event occurs.

>
> 4. What are the semantic restrictions on syntactically correct
> digitmaps?  For example, it doesn't seem valid to have more than one L
> or S in an alternative.

<MB> I don't actually understand the question. Please clarify.

Michael Brown