Response Codes

Response Code	Description
200	Success
400	Bad Request (Due to missing required fields)
401	Unauthorized (Invalid API Key or Invalid Signature)
408	Transaction Expired
409	Transaction Duplicate
499	Transaction is cancelled by Customer
502	Bad Gateway (Cannot connect to Service Provider)
503	Service Unavailable (Cannot send request to Service Provider)
504	Request Timeout
505	Authentication Failure (3DS flow or Not Supporter)