Please, read this:
Int32.MaxValue[
^].
Quote:
The value of this constant is 2,147,483,647; that is, hexadecimal 0x7FFFFFFF.
I would suggest to use string, because of different formatting. For example, if you want to make call to Poland, you need to provide a telephone number, like:
+48 000000000
- for mobile-phone.
Quote:
Most telephone networks today (exceptions being private intercom and secure phone networks) are interconnected in the international telephone network, where the format of telephone numbers is standardized by ITU-T in the recommendation E.164. This specifies that the entire number should be 15 digits or shorter, and begin with a country prefix. For most countries, this is followed by an area code or city code and the subscriber number, which might consist of the code for a particular telephone exchange. ITU-T recommendation E.123 describes how to represent an international telephone number in writing or print, starting with a plus sign ("+") and the country code. When calling an international number from a fixed line phone, the + must be replaced with the international call prefix chosen by the country the call is being made from. Some mobile phones allow the + to be entered directly.
More:
http://en.wikipedia.org/wiki/Telephone_number[
^]
http://en.wikipedia.org/wiki/Telephone_numbers_in_Poland[
^]