Fatal oci_connect error

Question

I have a bank oracle which is on a virtual machine, and I’m doing a university job I’d like to connect this web system to that bank.

Here comes the doubts, I need to install some application in the physical machine?

Follow my code php as follows:

$ora_senha="1234";

$oracle_bd="(DESCRIPTION=
                (ADDRESS_LIST=
                    (ADDRESS=(PROTOCOL=TCP)
                        (HOST=10.0.0.10)(PORT=1521)
                )
            )
            (CONNECT_DATA=(SERVICE_NAME=teste))
            )";

if ($ora_conexao = oci_connect( $ora_usuario, $ora_senha, oracle_bd) ){
    echo "conexão com o banco oracle foi feita com sucesso";
} 
else
  echo "erro na conexão com o banco";
?>

But oci_connect(); does not always connect from the following error:

"Fatal error: Call to Undefined Function oci_connect() in"

I’ve done everything, I’ve decoded the extensions on php.ini already downloaded the instantclient file but always get this error!