IDD Prefix (International Direct Dial):is what you have to dial before the country calling code while you call an international phone number. The (+) which you find it before any international phone numbers indicate to the IDD prefix which you have to dial before the country code . This IDD prefix is (00) in most countries of the world, but this IDD Prefix is different in an other countries like USA, which used 011 instead of 00. Therefor they write this Plus (+), because you have to enter IDD perfix before the country codes which used in your country, which is not the same as an other country (therefor this + is maybe 00 and maybe 001 or an other!) For example, if you want to dial a phone number in USA from Germany, you have to enter 00 as IDD prefix which is used in Germany, and then the USA country code which is the 1, therefor you have to dial 001xxxxxxxx. But if you are calling USA from Australia, then there is more than one IDD prefix in Australia ( 0011, 0015, 0018 and 0019 ), and therefor you have to dial one of the following: 0011-1-xxxxxxxxxx, 0015-1-xxxxxxxxxx, 0018-1-xxxxxxxxxx, 0019-1-xxxxxxxxxx. The IDD prefix from Japan has also more than one prefix and they are ( 001, 0061, 0041 and 010 ), therefor you have to dial one of the following: 001-1-xxxxxxxxxx, 0061-1-xxxxxxxxxx, 00411xxxxxxxxxx, 0101xxxxxxxxxx. That is the reason why you find always a Plus (+) before the international phone numbers (ex. +1xxxxxxxxxx).
IDD Prefix (International Direct Dial)*
Africa
Asia
Australia
Europe
North America
South America
