Redirecting the buyer to the payment page

The URL of the payment gateway is:
https://secure.payzen.eu/vads-payment/

Example of parameters sent to the payment gateway:
<form method="POST" action="https://secure.payzen.eu/vads-payment/">
<input type="hidden" name="vads_action_mode" value="INTERACTIVE" /> 
<input type="hidden" name="vads_amount" value="2990" /> 
<input type="hidden" name="vads_ctx_mode" value="TEST" /> 
<input type="hidden" name="vads_currency" value="978" />
<input type="hidden" name="vads_cust_country" value="DE" />
<input type="hidden" name="vads_cust_email" value="me@example.com" />
<input type="hidden" name="vads_cust_first_name" value="John" />
<input type="hidden" name="vads_cust_last_name" value="Doe" />
<input type="hidden" name="vads_cust_phone" value="+33102030405" />
<input type="hidden" name="vads_page_action" value="PAYMENT" />
<input type="hidden" name="vads_payment_cards" value="SOFORT_BANKING" /> 
<input type="hidden" name="vads_payment_config" value="SINGLE" /> 
<input type="hidden" name="vads_site_id" value="12345678" /> 
<input type="hidden" name="vads_trans_date" value="20190710101407" /> 
<input type="hidden" name="vads_trans_id" value="362812" /> 
<input type="hidden" name="vads_version" value="V2" />
<input type="hidden" name="signature" value="NM25DPLKEbtGEHCDHn8MBT4ki6aJI/ODaWhCzCnAfvY="/>
<input type="submit" name="pay" value="Pay"/>
</form>