PHP会话变量未成功传递

我第一次尝试使用PHP会话。例如，我想创建一个链接到一个名为音素搜索2.php的页面，该页面加载该页面并将变量phon1设置为"M"，phon3设置为"L"，phon4设置为"IY"。amd umatch改为"umatch"。因此，我链接到这个网址：

音素搜索2.php？phon1=M&phon3=L&phon4=IY&umatch=umatch

这是目标页面中的代码：

session_set_cookie_params(3600,"/");
session_start();
//submitted form variable definitions
if(isset($_POST['umatch']))
{
    $umatch = $_POST['umatch'];
} else {
    if( !isset($_SESSION['umatch']) )
    {
        $umatch = '';
    } else {
        $umatch = $_SESSION['umatch'];
    }
} 
$_SESSION['umatch'] = $umatch;

if(isset($_POST['phon1']))
{
    $phon1 = $_POST['phon1'];
} else {
    if( !isset($_SESSION['phon1']) )
    {
        $phon1 = '';
    } else {
        $phon1 = $_SESSION['phon1'];
    }
} 
$_SESSION['phon1'] = $phon1;
if(isset($_POST['phon2']))
{
    $phon2 = $_POST['phon2'];
} else {
    if( !isset($_SESSION['phon2']) )
    {
        $phon2 = '';
    } else {
        $phon2 = $_SESSION['phon2'];
    }
} 
$_SESSION['phon2'] = $phon2;
if(isset($_POST['phon3']))
{
    $phon3 = $_POST['phon3'];
} else {
    if( !isset($_SESSION['phon3']) )
    {
        $phon3 = '';
    } else {
        $phon3 = $_SESSION['phon3'];
    }
} 
$_SESSION['phon3'] = $phon3;
if(isset($_POST['phon4']))
{
    $phon4 = $_POST['phon4'];
} else {
    if( !isset($_SESSION['phon4']) )
    {
        $phon4 = '';
    } else {
        $phon4 = $_SESSION['phon4'];
    }
} 
$_SESSION['phon4'] = $phon4;
if(isset($_POST['phon5']))
{
    $phon5 = $_POST['phon5'];
} else {
    if( !isset($_SESSION['phon5']) )
    {
        $phon5 = '';
    } else {
        $phon5 = $_SESSION['phon5'];
    }
} 

当页面加载时，它不会合并URL中的变量值。所有变量均为空。我怎样才能让它们粘在一起？

谢谢！