how to consume this webservice soapclient in php?

Howtoconsumethiswebservicesoapclientinphp???Itriedthecodebelowandgavethefollowingerror.

Code

$client=newSoapClient('http://www.smsviaweb.com.br/SMSVIAWEB.asmx?wsdl');$params=array('Login'=>'xxxxx','Senha'=>'xxxxx','Telefone'=>'xxxxx','Mensagem'=>'xxxxx');$client->__soapCall("Envia", $params);

Error

  

Fatal error: Uncaught SoapFault exception: [soap: Server]   System.Web.Services.Protocols.SoapException: Server was unable to   process request. --- > System.NullReferenceException: Object reference   not set to an instance of an object. at SMSVIAWEB.Envia (OBJMsgSMSVW   OBJMsg) --- End of inner exception stack trace ---

getFunctions

 array(6) {
  [0]=>
  string(38) "EnviaResponse Envia(Envia $parameters)"
  [1]=>
  string(50) "EnviaLoteResponse EnviaLote(EnviaLote $parameters)"
  [2]=>
  string(62) "ExecutaImportResponse ExecutaImport(ExecutaImport $parameters)"
  [3]=>
  string(38) "EnviaResponse Envia(Envia $parameters)"
  [4]=>
  string(50) "EnviaLoteResponse EnviaLote(EnviaLote $parameters)"
  [5]=>
  string(62) "ExecutaImportResponse ExecutaImport(ExecutaImport $parameters)"
}
array(9) {
  [0]=>
  string(37) "struct Envia {
 OBJMsgSMSVW OBJMsg;
}"
  [1]=>
  string(127) "struct OBJMsgSMSVW {
 string Login;
 string Senha;
 string IDCliente;
 string Telefone;
 string Mensagem;
 string DataAgenda;
}"