function IsUSAPhoneNumber(str) {
	var supported = 0;

	if (window.RegExp) {
		var tempStr = "a";
		var tempReg = new RegExp(tempStr);
		if (tempReg.test(tempStr)) supported = 1;
	}

	if (!supported)
		return (str.length == 10);

	var r1 = new RegExp("^[2-9]{1}[0-9]{2}[0-9]{3}[0-9]{4}$");
	return r1.test(str);
}