Discussion List for Freenum/ITAD Subscriber Number (ISN) Project

[John Todd <>]

On Oct 29, 2009, at 7:52 PM, James Cloos wrote:

> > > > > > "John" == John Todd 
> > > > > > <>
> > > > > >  writes:
>
> John> I can completely understand the desire to have "0" as the main
> John> number of an organization, though maybe it shouldn't be the  
> "main
> John> number", but should be "human operator".  This still makes for
> John> very difficult dialplan interpretation for those who are not  
> using
> John> a fully SIP-compliant system (a "dial-as-you-go" interface  
> like an
> John> older ESS, which still runs the majority of the phones in the  
> world.)
>
> That is one of the bugs with choosing endian-little rather than big- 
> endian
> strings for the ISN format.
>
> I know that the idea was to emulate the format of email addresses  
> (perhaps
> indirectly, via the format of sip: urls?), but one can argue that  
> that is
> also a bug for email addresses.  And it never felt quite right to me.
>
> Emulating for big-endian format of most other urls would make for  
> (or would
> have made for) easier dialplans and also provide the conceptual  
> advantage,
> when phoning an organization, of thinking "this org" and then "this  
> person"
> or "this role".
>
> The ENUM lookup would be the same as now, only the advertising and  
> dialing
> order(s) of the number would be (or would have been) different.
>
> That is not to say that there would be no bugs with choosing the big- 
> endian
> order.  (Although I cannot think of any off-the-cuff. :)

I understand the shortcomings of the chosen method, but the hope is  
that eventually we'll all be dialing SIP URIs some day.  So, it's  
easier to explain and have people remember "An ISN is like an email  
address - username, then a separator, then a domain - except you can  
do it all from a standard 12-digit phone keypad."   The intent is to  
create a transition between E.164 and SIP URIs, so there is a  
structure that is similar to URI format rather than E.164 big-endian  
format.

There were other reasons, too, but it's 1:45 AM and I'm too tired to  
dredge them out of my memory.  :-)

JT