When using the US Unlocked Card as form of payment on US websites we always recommend to be connected over VPN. VPN means Virtual Private Network. A VPN connection works as a tunnel and converts your non-US IP address in a US IP address.
A VPN connection protects your computer and communications on the internet against hackers and security breaches and gives you access to websites that block purchases from non-US IP addresses. Also read VPN Offers Access to the Good Stuff