Some people might question why I format the numbers the way I do. Well, the rationale is to bring it as close to the ITU standards when formatting. I did wanted to make sure I separated the country code from the number, but with people using (), -, and . as their formatting, it would never be the way that everyone would write it. All of the extra characters are not ITU standard. Just the +, and numbers. With that in mind, I write my numbers as +(country code) subscriber number. Therefore, my cellular number will be +1 4126829751. As you can see, I just separate the county code from the rest of the number. This is designed to bring it as close to ITU standards.
Exceptions to this is my contact cards. Since I am not going to travel, everyone I would give a card to will likely live in the US. With that in mind, I place a space after the +1, third, and sixth numbers. VCF files combines the number entirely making it completely ITU standard.