Merchant Account is required to accept debit or credit card payment on your website. You have to make it sure you will use correct address details otherwise your card payment no not gone through. Also you have to make it sure your card is active to use on online website so call your bank and double check either your card it active or not.
It is compulsory to have ITIN number to get payment gateways in US including PayPal and Merchant Account.
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