A telephone numbering plan is a kind of numbering plan which is distributed in the telephone network in all over the world and the telephone network uses this common and general format to communicate between each other. There are two types of telephone numbering system. Number one is closed numbering plan and the other one is open numbering plan. The first one the closed numbering plan is found in north America. In the closed numbering plan the numbering scheme is fixed length and in the open numbering plan there are variation in the total number and this is not fixed.
This numbering plan includes a plan which is named as dial plan. Which includes the total expected number for a telephone to be allocated. This involves the country code, access code, area code and all combination of digits which needs to be dialed. the North American public switched telephone network (PSTN) uses a 10-digit dial plan that includes a 3-digit area code and a 7-digit telephone number. Most PBXs support variable-length dial plans that use 3 to 11 digits. Dial plans must comply with the telephone networks to which they connect.
Area codes are necessary when a telephone user make a phone call to a different country or outside his own country. To use the country code there is a standard to follow a “+” plus sign and with spaces in place of hyphens (e.g., “+AA BBB CCC CCCC”).This format gives the idea of a user that which number code he should follow to make an international dialing. In the case of GSM networks all over the world, “+” is a definite character that may be used internally as the international access code, rather than simply being a convention.
Area codes are in most of the cases know as numbering plan areas (NPAs) and formerly know as STD codes in UK and in India they still use the term STD. They are necessary when an user makes a phone outside the code area which is allocated previously. This may be from one state to another state. Area codes usually indicate geographical areas within one country that are covered by perhaps hundreds of telephone exchanges, although the correlation to geographical area is becoming obsolete.
Area codes are often used and coded using the international using the national access code. Suppose one is calling from one state to another in INDIA and he needs to put the area code as the call is from outside the area code so he needs to put the numbers like first the area code of the place then the number. Suppose one is calling from Orissa to Kolkata in India then at first 033 needs to be added as the code for Kolkata is 033 then the phone number like 8765 4321.If he is calling outside from the country then need to put the country code like +91 which is the country code for India then the code for Kolkata 33 no need to put the zero then the number. Area codes were first introduced in the United States by the Bell System, in 1947. The first direct dial long distance call occurred in 1951.
Although the International Telecommunication Union (ITU) has a common rule to use 00 for the country access code but no country is following this rule. The numbering plan is now different in different parts of the world. Some of the countries like united states ,Canada and other countries are participating the north American Numbering plan. The international numbering plan denotes country code that is area codes that represents a nation or group of nations.
This is the responsibility of each country to define the country code for its own purpose and to use it in its own network. It is important to get a clear idea about global telecommunication industry. For this some standards are formatted which are like below:
- A fixed length like 3 digits in United States and Canada, two digits in Brazil; one digit in Australia and New Zealand
- A variable length, e.g., between 2 and 5 in Germany, Argentina, United Kingdom and in Austria; between 1 and 5 in Japan; 1 or 2 in Syria and Peru
- In many cases this is incorporated in the subscribers number. This format is used in the countries like Norway and Spain. This number plan is know as closed numbering plan. In some codes this is must to dial a trunk code like 0 in some countries like Belgium. Hong Kong used an one digit area code of 1 and this was incorporated in the subscribers number so there was no need to dial it separately.
Pricing of a call depends on the area codes. This is the code which determines whether the call will be costly of cheap. The calls within the area code or in a small adjacent or overlapping area is not that much higher rate rather those are charged a low call rate. This is often not the case in the United States where rates to call within a state [regulated by that state’s public utilities commission] are often higher than rates to call across the country [generally determined by competition. Rates are determined from the rate centers. Special area codes are used to make free ,premium rate calls and mobile phone systems to land line. There are some exceptions where calls are charged irrespective of the area codes and charged equally regardless of the distance within the country. Egypt is the example of this type of country where calls are charged equally regardless of the distance and area code within the country.
An open dialing plan is a plan where there are different dialing plans for local and long distance dialings. This plan means that to make a call within a city a caller needs to call only the number and to make a call outside the area an area code is required to make those calls.
A closed dialing plan is a plan where a caller calls a fixed number regardless of the distance whether this is within the city or outside the area cause the area code is incorporated in the dialing number.
