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Cell Phone Plans
New Zealand |
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A telephone numbering plan is a
plan for allocating telephone number ranges to countries,
regions, areas and exchanges and to non-fixed telephone networks
such as mobile phone networks. A typical dialed telephone number
comprises digits that need not always be dialed (codes) and
digits that must always be dialed (local number).
Structure
The structure is:
Access code (either international or national) - only
necessarily when dialing international and "national" (non-local
domestic) calls. The national access code is often quoted as if
it were part of the telephone number. One of these access codes
must be dialed from mobile phones. The most common national
access code is "0", and the most common international access
code "00"; in the United States and Canada, however, "1" and
"011" are used, respectively.
Country code - only necessarily when dialing to phones in other
countries. It is often quoted together with the international
access code which must precede it in the dial string, especially
in the United States and Canada (e.g. "011-XX-YYY-ZZZ-ZZZZ"). In
international usage, telephone numbers are typically quoted with
the country code preceded by a "+", and spaces in place of
hyphens (e.g. "+XX YYY ZZZ ZZZZ"). (On GSM networks, "+" is an
actual character that may be used internally as the
international access code, rather than simply being a
convention.)
Area code - only necessarily dialed from outside the code area,
from mobile phones, and (especially within North America) from
within overlay plans. Area codes usually indicate geographical
areas within one country that are covered by perhaps hundreds of
telephone exchanges. It must usually be preceded in the dial
string by either the national access code or the international
access code and country code. Non-geographical numbers, as well
as mobile telephones outside of the United States and Canada, do
not strictly speaking have an area code even though they are
usually written as if they do.
Local number - must always be dialed in its entirety. The first
few digits in the local number typically indicate smaller
geographical areas or individual telephone exchanges. In mobile
networks they indicate the (original) network provider. Callers
from a number with a given area/country code usually do not need
to include this particular area/country code in the number
dialed, which enables shorter 'dial strings' to be used. This is
an issue when the number must be keyed by hand, but where the
dialing is automated (increasingly common) it is not an issue -
and it is arguably better to include the full number with access
codes in devices that dial automatically.
Standards
Although the International Telecommunication Union (ITU) has
attempted to promote common standards among nation states,
numbering plans take different formats in different parts of the
world. For example, the ITU recommends that member states adopt
00 as their international access code. However, as these
recommendations are not binding on member states, some have not,
such as the United States, Canada, and other countries and
territories participating in the North American Numbering Plan.
The international numbering plan establishes country codes, that
is, area codes that denote nations or groups of nations. The
E.164 standard regulates country codes at the international
level and sets a maximum length limit on a full international
phone number. However, it is each country's responsibility to
define the numbering within its own network. As a result,
regional area codes may have:
A fixed length, e.g. 3 digits in the United States and Canada; 1
digit in Australia.
A variable length, e.g. between 2 and 5 in Germany and in
Austria; between 1 and 3 in Japan; 1 or 2 in Israel.
Or be incorporated into the subscriber's number, as is the case
in many countries, such as Spain or Norway. This is known as a
"closed" telephone numbering plan. In some cases a trunk code
(usually 0) must still be dialed, as in Belgium, Italy, Poland,
Sweden, Switzerland and South Africa.
Generally the area codes determine the cost of a call. Calls
within an area code and often a small group of adjacent or
overlapping area codes are normally charged at a lower rate than
outside the area. Special area codes are generally used for
free, premium rate, mobile phone systems (in countries where the
mobile phone system is caller pays) and other special rate
numbers. There are however some exceptions, in some countries
(e.g. Israel), calls are charged at the same rate regardless of
area and in others (e.g. the UK) an area code is occasionally
treated as two parts with different rates.
Open dialing plans
An open dialing plan is one in which there are different dialing
arrangements for local and long distance telephone calls. This
means that to call another number within the same city or area,
callers need only dial the number, but for calls outside the
area, an area code is required. The area code is prefixed by a
trunk code (usually "0"), which is omitted when calling from
outside the country. |
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