31 May
2024
31 May
'24
9:57 a.m.
Ben Kaufman via sr-users <sr-users(a)lists.kamailio.org> writes:
Agreed of course on NANP vs US.
I would say that "NANP numbers" are 10 digits, period. However E.164
representations of those are 11 as they include the 'country code'.
Beware that in the US you must use a 1 before long distance (and now
most numbers), but this is a trunk access code and NOT a country code.
It just happens to be the same digit.
This point is important as on local phone lines people do not input
E.164 numbers directly.
They may enter 1+10digits as long distance. Sometimes 1+7, but that is
rarer now than it used to be. (Part of that is with portability, it's
now more of a flat 10-digit space; it used to be hierarchical.)
They may enter an international access code, 011 traditionally, + on
cellular and then E.164 number.
SIP trunks can be set up multiple ways. Including wanting bare E.164
with no +, always country code followed by in-country number.
I think the 10-digit representation is highly normal.
There is also the 7 digit number, and I think in many places if you are
very local and the numbers are all in the area code where they belong
then you can dial just 7, but this is only for old-school landlines.
Because of overlay area codes and portability, a 7-digit representation
is asking for trouble. So it is odd, and arguably not a good idea, to
publish/distribute other than 10.
I am unaware of other than 10 or 7 as more than rarely for conventions.
I do see the local 10-digit number written as
+1 617 555 1212
which is not really a 'local' number but a global representation. The +
is a clue that an E.164 number follows, and the 1 is a country code.
To dial it, you realize that you are in the NANP, remove the +1 as
telling you to dial international access code and country code, and then
add back a DIFFERENT ONE to be the LD access code.
US numbers are
fixed lenght 11 digits?
The USA is in the North American Numbering Plan (NANP). This includes USA, Canada,
much of the
Caribbean (Cuba, Jamaica, Barbados for example), some US territories in the Pacific
(Guam,
American Samoa). The NANP's "Country Code" is 1. In the USA and Canada
(I think the entirety
of the NANP) this is followed with a 3 digit area code (National Destination Number)
followed
by a 7 digit subscriber number. What is the
usual representation of a 'local' US number?
There is no consistent
answer. Consider that the oldest phone network is in the USA, and the
unplanned initial growth and many historic regional governing bodies it varies
massively. It
has also changed greatly over time. GENERALLY speaking people will use the 11 digit
number or
the 10 digit number (without the "1" country code), but there's not a lot
of rhyme or reason
as to which is preferred in one case vs another.