command=v&amount=<amount>&currency=<currency>&client_ip_addr=<ip>&description=<desc>&language=<language>&msg_type=SMS(&<property_name>=<property_value>)

$post_fields = array(
                     'command'        => 'v',
                     'amount'         => $amount,
                     'currency'       => $currency,
                     'client_ip_addr' => $client_ip_addr,
                     'description'    => $description,
                     'language'       => $language,
                     'msg_type'       => "SMS(&${property_name}={$property_value}"
                    );