Code:
$soapaction = "http://communicationoffice.nbs.rs/GetCurrentExchangeRate";

$wsdl = "https://webservices.nbs.rs/Com...tExchangeRateService.asmx?WSDL";
$namespace = "http://www.nbs.rs/TempExchangeRatesService";
$client = new soapclient($wsdl);

$mysoapmsg = $client->serializeEnvelope('<GetCurrentExchangeRates xmlns="http://www.nbs.rs/TempExchangeRatesService">
      <nExchangeRatesListTypeID>1</nExchangeRatesListTypeID>
    </GetCurrentExchangeRates>','<AuthenticationHeader xmlns="http://www.nbs.rs/TempExchangeRatesService">
      <UserName>myUserName</UserName>
      <Password>myPassword</Password>
      <LicenceID>myLicenceID</LicenceID>
    </AuthenticationHeader>',array(),'document', 'literal');

$response = $client->send($mysoapmsg, $soapaction);

if ($client->fault) {
echo '<h3>Fault</h3><pre>';
print_r($response);
echo '</pre>';
}
echo $client->response;