The country codes are a convenient, short-form way to tell a telephone service provider you’re calling from overseas. They’re simple, memorable and a proven international standard.
They originated in the 1950s as a way to reduce the amount of time required to enter numbers on rotary phones. They were developed by the International Telecom Union, which contains many countries’ network suppliers.
Country Codes
Country codes are a group of numbers you must enter before dialing the number for the country you call. For example, if you want to call the United States from another country, you would type +11 first to inform your phone that you are making an international call.
Countries are assigned country codes based on geographic regions and populations. They can be one or two digits, usually in the +2 to +256.
The International Telecommunication Union (ITU) assigns codes to all countries to allow a telephone number to be placed internationally without confusion with domestic calls starting with the same digits. The ITU also provides prefixes to amateur and experimental radio stations.
These codes are typically represented in two-letter, three-letter or numeric form using the ISO 3166-1 alpha-2 standard. This standard is more commonly used than other coding systems, such as the ISO alpha-3 or the ISO numeric standards.
International Calling
International country codes help the phone company know which country you want your call to be routed to. They’re used for long-distance and local calls and in VoIP services.
These codes are divided into digits arranged according to zones worldwide, and countries are assigned one, two or three-digit country codes for their zone. The earliest country codes were established in 1960 in a “Red Book” of recommendations and were later expanded by a new set published in 1964.
The resulting scheme was designed to prevent confusion when dialing a number from abroad – particularly in mechanical telephone exchanges, where significant digits were required. In addition, it ensured that no more than 11 digits could be dialed and thus prevented unnecessary calls.
To make an international call from a landline, dial the IDD prefix and the country code for the country you’re calling from. It is the same for making calls from mobile phones.
International Dialing Prefixes
International calling prefixes are a vital part of the dialing process. They typically indicate that you’re making an international call and help avoid confusion with domestic numbers starting with the same digits.
Often, this is followed by a country code. Almost every country in the world has its code, which can be up to three digits long.
Any country’s international call prefix usually consists of an IDD (International Direct Dialing) designation, an exit code and a national trunk prefix. These codes vary between countries and need to be clarified.
You have to remember that while utilizing international codes, call them without dialing the first 0 permanently. It is because the 0 (zero) is usually the trunk prefix and must be left out when you dial international numbers from another country. In addition, you should always use a country code when calling a specific country.
Area/City Codes
Area/City Codes are a type of phone number used to identify a particular region in a country. This number must often be dialed when calling from one area/city to another or a toll number in a different area/city.
Area codes were developed in the mid-20th century to replace dialing prefixes. These codes were introduced to help the telephone industry meet the growing demand for telephone numbers.
New area codes are given out when needed by the North American Numbering Plan Administrator (NANPA) based on use. NANPA also ensures that similar codes are not next to each other to avoid confusion.
Some area codes are set aside for particular purposes, such as time-of-day and weather forecasts, information provider service, high-volume calling, and emergency preparedness. These numbers are kept from general commercial use. When these numbers are not in use, they lie vacant. The CPUC must determine if these numbers are being utilized appropriately.
