Muse Test - Credit Card info

[Smiley]

In order to qualify a customer as a sale, is it necessary to ask for credit card details?
I ask this because at the moment, I have the sales letter for the landing page, which leads interested users to a second page where the price is revealed and their personal details are asked (name, phone, email). From here, the third page shows the back-order message.
I am wondering if it's important to ask the customer to enter credit card info, therefore ensuring that they are genuine sales.

Thank you for any help