The country code prefix for calling Isle of Man is +44 1624.
To make an international phone call, you should dial: "exit code of your country" + "country code of the country you are dialing to" + "the phone number you want to call".
For example: To call Isle of Man from the USA or Canada, dial: "011 +44 1624 + phone number"(011 is the Exit code of the USA)