Most commonly, merchants choose to use our Hosted Gateway to display invoices to their customers.
The url to display an invoice is sent in the Invoice::Create response, as the parameter `gateway_url`
Using the gateway is very simple. Simply redirect the customer to the `gateway_url` shown above.
If the Invoice is a Bill, the customer will be asked to choose a payment currency.
If the Invoice is in unpaid state, a QR code and payment amount/address will be shown. Additionally, the Gateway displays the 15 minute window in which the invoice payment will be accepted at the current GoCoin spot rate (guaranteed exchange rate).
When the invoice state (status) changes, the following will occur:
| Status | Event | Visual | Action |
| Paid | Payment Received | Paid state displayed | If a redirect_url was supplied, redirect to it. |
| Ready to Ship | None | Paid state displayed |
| Fulfilled | None | Paid state displayed |
| Underpaid | Payment Received | Underpaid state displayed, balance adjusts to remainder |
| Unpaid | Expired | Expired state displayed |