Subject: Digit Map Symbols

From: Tom-PT Taylor <[email-masked]>
Date: Tue, 11 Jan 2000 07:09:58 -0600

It has troubled me that the syntax for digit maps contains symbols which are
signalling system specific (particularly the MF symbols).  I propose the
following alternative:

1. The digit map symbol set consists of the digits "0" through "9" and "A"
through "F" (besides the extra stuff like "x", "L", and "S").

2. A package may define a mapping between events of that package and symbols
of the digit map symbol set.

Tom Taylor
Advisor -- IPConnect Standards
E-mail: [email-masked] (internally, Tom-PT Taylor)
Phone and FAX: +1 613 736 0961

---

From: Tom-PT Taylor <[email-masked]>
Date: Wed, 12 Jan 2000 08:49:59 -0500

Further to this proposal, here are the consequences for our protocol
document.

This first change comes from an E-mail I sent to our editors, giving my
comments on the latest draft:

7.1.14: the full semantics of digit map usage per the ABNF should be
explained.  Here is my attempt; please correct any errors.  It is designed
to fit just after the sentence: "Each string in the list is an alternative
numbering scheme, specified either as a set of digits or timers, or as a
regular expression of digits and timers."

<quote>

Within a string, the digits "0" through "9" and letters "A" through a
maximum value depending on the signalling system concerned, but never
exceeding "K", correspond to specified events within a package which has
been designated in the Events Descriptor on the termination to which the
digit map is being applied.  (The mapping between events and digit map
symbols is defined in the documentation for packages associated with
channel-associated signalling systems such as DTMF, MF, or R2.  Digits "0"
through "9" MUST be mapped to the corresponding digit events within the
signalling system concerned.  Letters should be allocated in logical
fashion, facilitating the use of range notation for alternative events.)
The letter "x" is used as a wildcard, designating any event corresponding to
symbols in the range "0"-"9".  The string may also contain explicit ranges
and, more generally, explicit sets of symbols, designating alternative
events any one of which satisfies that position of the digit map.

In addition to these event symbols, the string may contain "S" and "L"
duration modifiers.  An "L" designates a long event: placed in front of the
symbol(s) designating the event(s) which satisfy a given digit position, it
indicates that that position is satisfied only if the duration of the event
exceeds the long-duration threshold.  The value of this threshold is assumed
to be provisioned in the MG.  [What is "S" used for???]

Optionally, the expression defining the eligible set of events for a given
digit position may be terminated by a period.

</quote>

---------------

To go along with the above, we should add the following to section 12.1.3
within our guidelines for defining packages:

<quote>

For packages implementing detection of CAS signalling (for example, DTMF
detection), this section should also contain a mapping between events of the
package and the digit map symbols "0" through "9" and, as necessary, "A"
through "K".  As indicated in section 7.1.14, digits "0" through "9" MUST be
mapped to the corresponding digit events within the signalling system
concerned.  Letters should be allocated in logical fashion, facilitating the
use of range notation for alternative events.

This section MUST also define an event to be used to notify the MGC when a
digit map string has been matched by events of this package.

</quote>

We also need to add the mapping and digit map match event to the DTMF and R2
packages.

> -----Original Message-----
> From: Taylor, Tom-PT [CAR:B904:EXCH]
> Sent: Tuesday, January 11, 2000 8:10 AM
> To:   [email-masked]
> Subject:      Digit Map Symbols
>