Why do you need to use long when interpolating?

Question

C++ / C#

When formatting an array of numbers into a phone number, ToString() only works with long.Parse. Why? We get a string when using Concat, why doesn't he like it?

private string CreatePhoneNumber(int[] number)
        {
            return long.Parse(string.Concat(number)).ToString("[phone]");
        }

Answer 1

Because your number with 9XX-* doesn't fit into int32 space