How to pass post to PhoneGap?

Question

phonegap

Good afternoon, please tell me how to perform the data transfer from the form.
index page

<form name="MyForm"  id="callbacks" method="post"><!--Атрибут action остается пустым-->
  <input name="name" type="text" placeholder="Имя" /><br>
  <input name="tel" type="phone" placeholder="Телефон" /><br>
  <textarea name="body"  placeholder="Ваше сообщение"></textarea><br>
  <input type="submit" value="Отправить заявку" id="btncontcall" />
</form>

js file

$(document).ready(function() {
    $('body').on('submit', "#callbacks", function(e){ 
      var form = $(this).serialize();
     
      e.preventDefault();
      $.ajax({
        type: "POST",
        url: "http://*********/send.php", // Адрес обработчика
        data: form,
        
        error:function(){
           
          $("#erconts").html("Произошла ошибка!");},
        beforeSend: function() {
          $("#erconts").html("Отправляем данные...");
        },
        success: function(result){
         
          $("#erconts").html(result);
          checkThis();
        }
      });
      return true;
    });
  });

send.php

header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: POST,GET,OPTIONS');
header('Access-Control-Allow-Headers: Origin, X-Requested-With, Content-Type, Accept');
header('Content-Type: application/json');
 $a = $_POST["name"];
 $phone = $_POST["tel"];
 $body = $_POST["body"];
...дальше я их сохраняю в файл.

In the web version, everything is fine, data is sent from the computer, but when I start it from a mobile phone, nothing happens. What could be the problem? Which way to dig..