Jquery ajax: data arriving to server with "POST", but not arriving with "PUT"

Question

I am consuming a service from a REST api, and all types of request except "PUT" work. Apparently, when using PUT, the headers (data) are not arriving to the server, so authentication is no possible. If I send the data in a query string inside the url, the server behaves as expected. Why is the data not getting there?

// here is my ajax POST call.. it works as expected
function testPost(deviceId, segmentId) {
    console.log('inside testPost function');
    var url = "http://........../api/avoidsegments/" + deviceId;
        $.ajax({
        url: url,
        type: "POST",
        crossDomain: true,
        dataType: "json",
        data : {
            "appID": ig_appID,
            "clientCode": ig_clientCode,
            "segmentID": segmentId,
        },
        success: function(output) { 
            console.log(output);
        },
        error: function(err) {
            console.log('url: ', url);
            console.log('error: ', err);
        }
    });
}

And, here is the put request (I basically copied and pasted post, and changed the method type).. Why does this not send the data to the server??

function testPut(deviceId, segmentId) {
    console.log('inside testPut function');
    var url = "http://........../api/avoidsegments/" + deviceId;
        $.ajax({
        url: url,
        type: "POST",
        crossDomain: true,
        dataType: "json",
        data : {
            "appID": ig_appID,
            "clientCode": ig_clientCode,
            "segmentID": segmentId,
        },
        success: function(output) { 
            console.log(output);
        },
        error: function(err) {
            console.log('url: ', url);
            console.log('error: ', err);
        }
    });
}

Whenever I use "PUT", I get a 401... because the data is not arriving. I checked $_GET and $_POST where the put is handled and they are empty. If I send the data in a query string, put works as expected... I just doesn't work when I send headers.

I'd appreciate if anyone could point me towards the right direction so I can fix this problem.