Passing variables between jQuery and PHP on Post - php

Question

I have an $.ajax function that posts to a php page and gets some results.
function GetLicenseCount(SoftwareNameFK, SoftwareTypeFK,LicenseMethodFK,MinistryFK )
{
$.ajax({
type: "GET",
url: "modules/SoftwareLicenseAllocations/GetLicenseCount.php",
data: {SoftwareName : SoftwareNameFK, SoftwareType: SoftwareTypeFK, LicenseMethod: LicenseMethodFK, Ministry: MinistryFK},
dataType: "json",
success: function(result) {
var LicenseCount = document.getElementById("txtLicenseCount");
var idHidden = document.getElementById("txtId");
//get id value from string, by using split and getting the first part before the delimeter
var id = result.split(",")[0];
//get second part of result using string
LicenseCount.value = result.split(",")[1];
idHidden.value = id;
},
error: function(reason) {
console.log(reason);
alert("Failed to get License Count");
}
});
}
GetLicenseCount.php
<?php
//Local include path format
set_include_path('C:\PROJECTS\BRIAN\AMS\Web Application;C:\PROJECTS\BRIAN\AMS\Web Application\inc\pear;C:\PROJECTS\BRIAN\AMS\Web Application\js;');
//Search Screen
require_once('vars.php');
require_once('funcs.php');
//read the parameter passed through URL
$SoftwareName = $_GET['SoftwareName'];
$SoftwareType = $_GET['SoftwareType'];
$LicenseMethod = $_GET['LicenseMethod'];
$Ministry = $_GET['Ministry'];
//formulate query - get all active departments
$queryString = "SELECT DISTINCT id, LicenseCount"
. " FROM SoftwareLicenseAllocations WHERE"
. " SoftwareTypeFK =" . $SoftwareType
. " AND SoftwareNameFK = " . $SoftwareName
. " AND LicenseMethodFK=" . $LicenseMethod
. " AND MinistryFK=" . $Ministry;
// $queryString = "SELECT DISTINCT LicenseCount"
// . " FROM SoftwareLicenseAllocations WHERE"
// . " SoftwareTypeFK =" . 2
// . " AND SoftwareNameFK = " . 2
// . " AND LicenseMethodFK=" . 2
// . " AND MinistryFK=" . 1 ;
$sla = GetOpenItDataSet($queryString);
//loop on result set to refresh the department options list
while ($row = mysql_fetch_array($sla))
{
$LicenseCount = $row["LicenseCount"];
$id = $row['id'];
}//endWhile
$_SESSION['id'] = 22;
//echo $departmentArray;
echo json_encode($id . "," . $LicenseCount);
//$_POST["lcID"] = $id;
I am trying to get one of the values passed on in the original page.
i tried using $_Session on GetLicenseCount.php but the variable remains null.
Is is possible to pass a variable from jQuery to PHP? If so, how?
EDIT:
The problem is that GetLicenseCount is supposed to pass id, which it is doing, but I cannot use it in the original page via PHP, only via jQuery. When I come to use the $_SESSION['id'] through the original/previous php page it remains null.. The jQuery block is contained in another php page.