Some people might question how come I format my telephone numbers the way I do. The reason for this is to get close to ITU (International Telecommunications Union) standards. The only difference, is I would put a space between the country code, and the subscriber number. In example, my voicemail number is +1 4123608462. As you can see, there is a space after the 1 to show the country code. While this technically does not matter, I feel it is good to distinguish the country code since the country code varies from 1 – 3 numbers, and someone may not know if it is a 2 or 3 digit country code.
Exceptions to this is my contact cards. After the country code, I place a space after the 3rd and 6th number. This is to make it as easy as possible for someone that is used to seeing telephone numbers in such a format. I am not likely to give a contact card to someone outside of the NANP.