[asterisk-users] Please some enlightment on ENUM !!

[John Novack]

Raimund Sacherer wrote:
>> Adding random digits to a PSTN and expecting to get the same person at a
>> different extension....  you don't think that's a hack? I do. One should
>>     
>
> Sorry, please do not call a whole country using a hack when their solution is
> legitimate.
>
> Austrian PSTN
> https://supportforums.cisco.com/docs/DOC-1343
>
> Excerpt:
> Dialplan
> The Austrian dialplan is a variable length numbering plan, which consists of area codes and subscribers numbers. Area Codes are from 1 to 4 digits in length, subscriber numbers vary even more. Some Numbers (mostly used by companies) allow the use of Direct Inward Dial Extension. If such a number is used, it is up to the company to decide on the length of extensions, meaning that any length can be used.If too long extensions are used, the numbers might not be reachable from some sources. This is especially relevant with regard to number presentation inside of isdn, as stated under "Voice Interfaces and signalling".
>  
> A copy of the Austrian dialplan is maintained by the austrian regulatory council at http://www.rtr.at/en/tk/nationaleRufnummern.
>
>
> The emphasis on "variable length numbering", if you consider that austria is a small country which is physically not able to harbor more than 16 million peoples in a sane way, the numbering plan is more then sufficient, austria is not like germany with > then 88 million inhabitants which needed a reconfiguration of their numbering plan some years ago.
>
> my 2cents
>
> Raimund
>   
For those who have no background in telecom history, this may seem 
strange, but in fact in bygone years this was not JUST Austria that had 
this scheme. In the Electro-mechanical days what some of us know as 
Direct Inward Dialing ( not the DID term often misused in modern times ) 
was handled this way in open numbering plans.
It is unfortunate, but all too common, that in a great many fields,very 
smart educated people are ignorant of the history of their field, and 
are doomed to re-invent the wheel, or proceed down a blind alley.

In North America, with a closed numbering plan, all numbers are of a 
fixed length, 10 digits. Technically the "one" is NOT part of the 
number. In earlier days, no "one" was needed even for toll calling to 
distant cities and area codes. Some, fewer each year, are able to dial 
within their NPA with 7 digits. with the NANP turned over to the inmates 
( the state PSC's ) some locales require 11 digits for all calls, others 
10 for local, 11 for toll, and others 10 digits for all calls.
The closed number plan is somewhat easier to parse, with its fixed 
length, and no timeout or send/end digit is needed. the open plan can be 
more efficient in use of numbers. Different locale dialing pattens do 
make that more of a challenge, however.
How all of this works in regard to ENUM is for others to decide, but if 
it cannot handle an open numbering plan with variable length numbers it 
needs fixing.

John Novack 

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