The most convenient place to find international dialing codes is on phone carrier websites, including AT&T and Sprint. Each website provides a full listing of codes for quick reference.
A dialing code is essential to making international phone calls. When a user inputs a code, it automatically connects the circuits for the target country. The remaining digits help locate the correct phone. The country code for the United States, for example, is 1.
When dialing an international number from the United States, most phone service providers require callers to add "011" before the target country's dialing code. This step lets the system know that the user is calling a number out of the North American service network. On digital phones, users can input the plus sign in place of the "011."
The rules change for travelers who are using their carrier's international roaming services. When roaming in other countries, the phone automatically picks up local networks. As such, users do not need to use that country's dialing code to call local phone numbers. When travelers are near international borders, they may pick up a network in another country; to solve this problem, most carriers have an instructional website page to help find the correct dialing structure.