Country codes never begin with zero. In this example, '00' is a commonly used international access prefix and the actual country code is +39, which is Italy.
Additionally, you need to know that Italy is an exception to the usual rule that you drop the leading '0' of the domestic area code when calling internationally. For example, the area code for Rome is 06, but internationally it is +39 06, not +39 6.
To call Rome from the US, dial 011 - 39 - 06 - (local number in Rome).
(The plus sign means "insert your international access prefix here." From a GSM mobile phone, you can enter the number in full international format, starting with the plus sign. The most common prefix is 00, but North America (USA, Canada, etc.) uses 011, Japan uses 010, Australia uses 0011, and many other countries use different prefixes.)
To dial out of the US, first dial the international access code (usually 011), then the country code of the country you are calling, followed by the area code and phone number.
To dial out of the US, first dial the international access code (usually 011), then the country code of the country you are calling, followed by the area code and phone number.
To dial outside the US, first dial the international access code (usually "011" in the US), then the country code of the country you are calling, followed by the local phone number.
To dial outside of the US, you typically need to dial the international dialing code (usually "011"), followed by the country code of the country you are calling, and then the local phone number.
1 is the country code of the US. If you are outside of the US, you must dial 1 before any number to reach any number within the US. Every country has a different country code that you add to the beginning of a number in that country to dial a number in that country.
To dial China from the US, first dial the international access code (011), then the country code for China (86), followed by the area code and phone number.
To dial China from the US, first dial the international access code (011), then the country code for China (86), followed by the area code and phone number.
To dial from the US to Australia, you need to first dial the international dialing code, which is 011. Then, dial the country code for Australia, which is 61. Finally, dial the area code and phone number you wish to reach in Australia.
To dial out to Australia from the US, you need to first dial the international dialing code "011" followed by the country code for Australia which is "61." Then, dial the area code and phone number you wish to reach in Australia.
To dial Singapore from the US, first dial the international access code (011), then the country code for Singapore (65), followed by the local phone number in Singapore.
To dial Australia from the US, you need to first dial the international dialing code "011" followed by the country code for Australia, which is "61." Then, dial the Australian phone number you wish to reach, including the area code.
To dial Australia from the US, you need to dial the international dialing code 011, followed by the country code for Australia which is 61, and then the Australian phone number you wish to reach.