|Newer page:||version 5||Last edited on Friday, September 18, 2009 11:31:32 am||by GerwinVanDeSteeg|
|Older page:||version 4||Last edited on Friday, August 14, 2009 4:36:39 pm||by GerwinVanDeSteeg||Revert|
@@ -13,17 +13,23 @@
If we received a Caller-ID for the callee as 99740000 for example at a first glance we would recognize that as a Auckland NZ number. However, if we get a Caller-ID for example of 8001234567, you'd expect that to be a NZ 0800 number, however 8001234567 also matches the UIFN range of International Free Phone numbers. There's no way to distinguish between the two in that format, and what we have here is a number space clash between the International country calling code prefixes and a national number prefix.
__Q__: How about if we prefix it with a 0?
for ''most'' cases, there are however
local area codes around the world which do have a 0 in them. In New Zealand we have the 02
, 03, 04, 06, 07,09 local area codes where the initial 0 is the local access code. Certain countries use 2-3 digit area codes, and if using their local 0 access code
. Stripping away
the local 0 access code
for that country, we are still left with a 09 prefix. And again would result in a number space clash
+__A__: This for local , you get for . the for that .
__Q__: How about if we use the length of a number to distinguish between number space clashes
__A__: Again this works in ''most'' cases, for example in the 800 range described earlier the UIFN number is 800 with 8 additional digits, whilst the NZ 800 numbers have an additional 5-7 digits (there is a clash here between the Number Administration Deed document which states exactly 6 digits, and the NZ Dialplan provided to the ITU by the NZ Goverment which provides a range of 5-7 digits). A case where it does not work for example is the 230 number range, which is defined in NZ as part of the 23 number range with 6-7 additional digits, and Mauritius which has a country code prefix of 230 with an additional 6 digits to indicate the local number. And yes, the 023 number range in NZ has been allocated to a TelCo, it is not quite yet in use.
__NB__: As for number length, I don't think you'd want to program the dialplan for your local region into your PBX especially not if your developing a commercial product with International customers.
By using the E164 recommendation you avoid any number space clashes between National and International numbers.