ISD Codes, International Phone Codes

Below you see a list of ISD Codes, International Phone Codes. The list includes also the International Dialing Prefix (IDD) and the Country Calling Code by country. 
Almost each country in the world has its own country calling code, it is a single- or up to three-digit number which you have to dial to make a call to that country.
Make an international call:
First you dial the prefix-number (for most countries 00)  then the calling code number for the country   the area code (the city or region (for landlines only))   last not least: the user number. 
International Calls made easy
* The Dialing Country Code is the prefix number you have to dial to connect your call to the specific country you want to call.
** The International Call Prefix (also called an international access code or an International Direct Dialing code - IDD) is a telephone dialing code used to dial out of a country when making an international call. 
In given phone numbers the IDD is often abbreviated by just " " like in 0123 456 789, to signify that the caller should use the appropriate prefix for the country from where he is calling. 
*** National Code (like an Area Code) is the local number within the North American Numbering Plan (NANP) related to island nations and US dependencies in the Caribbean and the South Pacific.
International Calls made easy.
In principle, it's straightforward like you call from your landline or mobile at home. The only difference is, you have to dial some prefix numbers and leave out the leading zero (if any) in the area code or the mobile phone number. 
It looks like: 
Access code (IDD) country calling code area code (if any) subscriber's phone number 
example US/Canada: 011 country code area code subscriber's phone number
example Europe: 00 country code area code subscriber's phone number
Let's say you want to telephone from country A (the country where you are) to country B (the other country where you want to call to).
I. the first number you have to dial will be the International Dialing Prefix (IDD) of country A to indicate it is an international call (out of the country), in the majority of cases this will be "00", in Canada and the US "011", however, please check the IDD list above.
II. then you dial the Dialing Country Code alias Country Calling Code, the number which is designated to country B (see list above)
III a (for landlines)
then you dial the phone number of the called party, (the person or company you want to call), this number is made up of: the area code (NOW without the leading zero!) for a city or region within the foreign country and the unique number (subscribers number) of the called party, the number of your uncle Tom.
If you don't know the area (city) code, try a search engine like Google by searching for "area (or dialing) code for city/town name," use this number without! the leading zero.
III b (for cell phones)
then you dial the phone number of the mobile phone you want to call (without the leading zero).