$client = new SoapClient('http://magentohost/api/soap/?wsdl');

// If somestuff requires api authentification,
// then get a session token
$session = $client->login('apiUser', 'apiKey');

$result = $client->call($session, 'customer.info', '2');
var_dump($result);

// If you don't need the session anymore
//$client->endSession($session);

$proxy = new SoapClient('http://magentohost/api/v2_soap/?wsdl'); // TODO : change url
$sessionId = $proxy->login('apiUser', 'apiKey'); // TODO : change login and pwd if necessary

$result = $proxy->customerCustomerInfo($sessionId, '2');
var_dump($result);