Every country has a prefix for telephone calls, in much the same way as each area in the USA has area code. Also, most countries require a code to dial out. With increased travel, and usage of cell phones, it has become more common to keep in touch with people or businesses within the USA while overseas.
Use of Telephone
Select the 10-digit number of the person you wish to call, as if you were calling from within the United States.
Add 1 to the beginning of the number. This is the prefix for calling the USA from overseas.
Determine what the exit code is for dialing out of the country you are phoning from. In many countries it is "00." Find a list of the codes at sites such as Howtocallabroad.com. So to call from England to Manhattan, for example, you would dial 00-1-212-XXX-XXXX.
Dial the number.