function checkPhoneNumber(phone) {
    var regexp = /^(?:(?:\(?(?:00|\+)([1-4]\d\d|[1-9]\d?)\)?)?[\-\.\ \\\/]?)?((?:\(?\d{1,}\)?[\-\.\ \\\/]?){0,})(?:[\-\.\ \\\/]?(?:#|ext\.?|extension|x)[\-\.\ \\\/]?(\d+))?$/i
    if (regexp.test(phone) && phone.length > 0) {
        return true;
    } else {
        return false;
    }
}

Quick cheat sheet

  • Start the expression: /^
  • If you want to require a space, use: [\s] or \s
  • If you want to require parenthesis, use: [(] and [)] . Using \( and \) is ugly and can make things confusing.
  • If you want anything to be optional, put a ? after it
  • If you want a hyphen, just type - or [-] . If you do not put it first or last in a series of other characters, though, you may need to escape it: \-
  • If you want to accept different choices in a slot, put brackets around the options: [-.\s] will require a hyphen, period, or space. A question mark after the last bracket will make all of those optional for that slot.
  • \d{3} : Requires a 3-digit number: 000-999. Shorthand for [0-9][0-9][0-9].
  • [2-9] : Requires a digit 2-9 for that slot.
  • (\+|1\s)? : Accept a “plus” or a 1 and a space (pipe character, |, is “or”), and make it optional. The “plus” sign must be escaped.
  • If you want specific numbers to match a slot, enter them: [246] will require a 2, 4, or 6.[77|78] will require 77 or 78.
  • $/ : End the expression

ref: http://stackoverflow.com/questions/14639973/javascript-regex-what-to-use-to-validate-a-phone-number