Payment Verify Order Page (callback_verify_order)

AltaPay can callback the merchant just before a financial transaction is about to take place. This happens after the customer has typed in their card details or identified themselves with the alternative payment provider, which means the callback holds information about the card details if it is a card payment.

This enables merchants to abort the payment before it happens, which can be crucial for:

• Fraud checks
• Last second stock check (most retailers don’t reserve stock until payment)
• Ensuring that an applied discount is still valid
• Back-end updates
• Timers before you expect the payment finalised

It minimises refunds and it does not confuse customers by displaying a transaction on their bank statement.

This URL is called just before the payment is processed.

• To return a value that is not part of the normal POST parameters, you can prepend GET parameters to the URL.
• To allow the payment to proceed, you must return a HTTP response with code 200, and a HTML/TEXT response with the value "OKAY". Anything else results in an error message, and an aborted/declined transaction.

If the payment fails, the first 255 characters of your response is shown as an error message to the customer.