[Serusers] Prefix to Domains vs ENUM

[Alexander Mayrhofer]

On (10.11.03 19:04), Alessio Focardi wrote:
> AM> +878 could, for example, be an option for people who currently don't
> AM> have an ENUM trial active in their country... got it?
> 
> On to the pratical question:
> 
> I want to launch a free sip directory here in Italy.
> 
> what could be the next logical step to that my numbering plan will be
> coerent to future scenarios ?
> 
> I'm going to assign every user a 6 digits username, that's pretty plain.

Ok, from my opinion:

Don't hand out any numbers starting with 0 (access code), 1 (service
numbers in EU) and probably 9 (US service numbers). Your users will 
probably ask for vanity numbers, so if you decide to hand out such 
numbers, "9" cannot be excluded easily ("WXYZ" map to "9").

> Beside this, I'm pretty confused:
> 
> sipphone.com states that his prefix is 1-747-474, so if they are not
> partecipating in ENUM it seems logical to me to use uri conversion to
> append "@sipphone.com" to every number that begins with "1-747-474".

If they have the same numbering scheme for PSTN and SIP access, yes. If
not, it's not that easy. if, e.g. a user using 1-747-474-1234 as PSTN
number and using 4321 at sipphone.com as URI, it does not work out...

> What for addaline.com that does not state any prefix ? I have to choose one
> that I like ?

I'd choose one which doesn't clash with any country code. But keep in mind
that your users will probably some day use the same dialing plan as
the're used to on their regular phones, so it's not that easy. If you
think of a dial plan as like as:

2-9: Dial to other users
0: Dial out to national PSTN destinations
00: Dial out to international PSTN destinations

you have not much space left for prefixes. Using "1" could be dangerous,
because it clashes with service numbers (EU emergency calls 112, white
pages 118xxx, and so on...).

An option could be to use the Asterisk "*" to signal prefixes, e.g.:

*01*xxxxx -> sipphone
*02*xxxxx -> addaline

Thats obviously only good enough for 100 prefixes ...

We're using the "mobile phone" dialing plan here, so you cannot dial
any other "extension". You have always to dial the area code as well
("059966366003" from one phone to another instead of just "366003"). That 
gives huge opportunities in the dial plan (uses only 10% of the dial plan
space, but is only possible if you have numbers which are valid in the PSTN 
as well (otherwise they would clash with dialout to PSTN numbers). And 
best of all, people are used to that dial plan, because everybody 
uses mobiles ...

> And for my future plans ...
> 
> Do I have to apply now (if possibile) for an +878xxxx prefix
> or I can just invent one, hoping that when they will become public
> avalaible I will retain mine?

The number space "below" +87810 is exactly 15 digits, so you would have
something like: 

+87810xxxxyyyyyy

I'm not too familiar with the VisionNG policies, but i can direct you to
someone if you're interested. 

> Again, tnx, If you will ever come to Florence you will have someone to
> show you the city ! :)

will remember that, was in Siena last year. Never visited Florence,
though ...

cheers

axelm