jQuery - click event fire twice

jQuery - click event fire twice

Hi,
I have a problem with my jQuery click event. I have on my page an input type=button and when i click the button the click event happens twice.
here is my code:
my input button:

<input type="button" name="UDRaddPhone" class="buttonAddPhoneEnabled" id="UDRaddPhone_but" value="Add" />

and this is my jQuery :

$("input#UDRaddPhone_but").click(function() {
// validate and process form
// first hide any error messages
$('.error').hide();
var phoneType = $("select#UDRphoneType").val();
var phone = $("input#UDRphone").val();
if (phone != "")
if (phoneType == "Select phone type...") {
$("label#UDRphoneType_error").show();
$("select#UDRphoneType").focus();
return false;
}
if (phoneType != "Select phone type...")
if (phone == "") {
$("label#UDRphone_error").show();
$("input#UDRphone").focus();
return false;
}
$.ajax({
type: "POST",
url: "udr_register.aspx/AddNewPhoneNumber",
data: "{'tel_type':'" + $("select#UDRphoneType").val() + "','tel_number':'" + $("input#UDRphone").val() + "'}",
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function(msg) {
alert(msg.d);
if (msg.d == 1) {
$("label#UDRphoneExists_error").show();
document.getElementById("UDRphoneType").value = "Select phone type...";
document.getElementById("UDRphone").value = "";
return false;
}
else {
document.getElementById("UDRphoneType").value = "Select phone type...";
document.getElementById("UDRphone").value = "";
}
}
}
});
return false;
});
Here i'm calling a WebMethod and i send 2 parameters and the method is returning me an confirmation variable:1 if the phone number exists in database an 0 if not.

Thanks.