jQuery.AJAX is sending POST as GET

jQuery.AJAX is sending POST as GET

I have a number of helper functions on my website to process forms and submit to a web service running on another system. Despite changing method types, I can't get the requests to go through as POST, or PUT. I'm sure I've set the option correct, but nothing has changed.
  2. function sendRequest(path, requestMethod, parameters, callback) {
  3. var requestURL = serverBaseURL + path;
  5. console.log("Sending request to "+requestURL);
  6. console.log(parameters);
  8. var requestSettings = {
  9. type: requestMethod,
  10. data: parameters,
  11. success: callback,
  12. dataType: "jsonp",
  13. error: function(e) {
  14. console.log("Request error: "+e);
  15. }
  16. }
  18. console.log(requestSettings);
  19. $.ajax(requestURL, requestSettings);
  20. }

  22. function sendPOSTRequest(path, parameters, callback) {
  23. sendRequest(path, "POST", parameters, callback);
  24. }

the parameter "parameters" is a JSON object -> { lastname: "last", firstname: "first"} and callback is an anonymous function. I think the problem is something to do with the way jQuery is encoding the data, perhaps it's not compatible with sending POST messages. Any suggestions?