A phone number is a string of specific numbers that a caller can dial to reach another telephone or mobile phone. A phone number is sometimes referred to as a “DID“, which stands for Direct Inward Dialing. Phone prefix

When calling a phone number in another country, there is usually a prefix you have to dial to indicate that you’re placing an international call; this varies by country. After that international dialling prefix, you must dial the international country code for the country you are calling, followed by the local number.

There are 9 calling zones:

• 1 – United States, Canada, and several Caribbean nations share the international calling code 1, with each US state (or parts of US states), province, territory, or island nation given its own three-digit “area code”. The following list includes the area codes for such nations outside the US and Canada, as well as those of US possessions outside of the United States proper.
• 2 – Africa and some others like Greenland, Faroe Islands and Aruba.
• 3 – Europe
• 4 – Europe
• 5 – South America
• 6 – Southeast Asia and Oceania
• 7 – Russia, Kazakhstan and parts of Abkhazia
• 8 – East Asia and some services like Inmarsat
• 9 – Central Asia, South Asia and West Asia

Country calling codes or country dial-in codes are telephone number prefixes for reaching telephone subscribers in the networks of the member countries or regions of the International Telecommunication Union (ITU). The codes are defined by the ITU-T in standards E.123 and E.164. The prefixes enable international direct dialing (IDD), and are also referred to as international subscriber dialing (ISD) codes. phone prefix

Country codes are a component of the international telephone numbering plan, and are necessary only when dialing a telephone number to establish a call to another country. Country codes are dialed before the national telephone number.

By convention, international telephone numbers are represented by prefixing the country code with a plus sign (+), which also indicates to the subscriber that the local international call prefix must first be dialed. For example, the international call prefix in all countries of the North American Numbering Plan is 011, while it is 00 in most European, Asian and African countries. On GSM (cellular) networks, the prefix may automatically be inserted when the user prefixes a dialed number with the plus sign. phone prefix