A US number in international format is written by adding “+” which represents the exit code, followed by “1” – the US country code. After that, the rest of the numbers, e.g. (123) 456-7890, are US national digits. So, a US number would look like “+1 (123) 456-7890.” Remember: the hyphens and parentheses aren’t a part of any number. They’re being used here as delimiters.