Dialing telephone calls from the USA to Monaco
011
▶ 377
▶ city code
▶ local number
Step-by-step
011
▼ This IDD (International Direct Dial) prefix tells the phone system in the USA that you are dialing an international number.
377
▼ Country code for Monaco.
city code
▼ local number
Notes
Not sure what time it is on the other end of the line? Look here for Monaco time, date, and time zone information.
If you are calling from a hotel or office phone system, additional steps may be required.