<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope" xmlns:pos="http://PostWebService.org/">
   <soap:Header>
      <pos:Authentication>
         <!--Optional:-->
         <pos:UserName>xxxxxxx</pos:UserName>
         <!--Optional:-->
         <pos:Password>yyyyyyyy</pos:Password>
      </pos:Authentication>
   </soap:Header>
   <soap:Body>
       .....
   </soap:Body>
</soap:Envelope>

$client = new SoapClient({soapurl},$params);
$auth = new stdClass();
$auth->UserName = 'xxxxxxx';
$auth->Password = 'yyyyyyyy';
$header = new SoapHeader('NAMESPACE','Authentication',$auth,false);
$client->__setSoapHeaders($header);

$result = $client->__soapCall('{soap function}',array()); // when this line executes it throws me the error "Could not connect to the host"

$opts = array(
        'ssl' => array('ciphers'=>'RC4-SHA', 'verify_peer'=>false, 'verify_peer_name'=>false)
    );
    // SOAP 1.2 client
    $params = array ('encoding' => 'UTF-8', 'verifypeer' => false, 'verifyhost' => false, 'soap_version' => SOAP_1_2, 'keep_alive' => false,'trace' => 1, 'exceptions' => 1, "connection_timeout" => 180, 'stream_context' => stream_context_create($opts) );
    $client = new SoapClient({soapurl},$params);

   //Remaining as the same above