PUT 401 (Unauthorized) error in AngularJS request

I have a PUT request in AngularJS to update some information of a particular element, so my request calls a ASP.NET web service in that does that.

This is the code of my request:

$http({
        method : "PUT",
        url : "http://server/servicename/WebService.asmx/Update_Information",
        params: {Id: $scope.selectedId, Type: $scope.selectedType, Quantity: $scope.Quantity, Enabled: $scope.enabled, accessibility: $scope.accessibility}
      }).then(function mySuccess(response) {
        console.log("OK", response)
      }, function myError(response) {
        console.log("Failed", response);
      });

The web service works fine when I try itdirectly from http://server/servicename/WebService.asmx but when i launch it from my website the response is the following:

PUT 401 (Unauthorized)

But actually I'm not using any authentication or login in my website. Do I need pass the user and password of the database in my request? Or maybe I'm missing some security configuration on the ISS Server?