In CallHub, you can run campaigns by purchasing credits with the "Pay as you go" plan. You may use a Credit or a Debit card to make the payment.
You can recharge/add credits to your account by clicking the "$" sign after logging into your account.
Next, you need to navigate to the "Recharge" section and select the amount you wish to add.
Once you have selected the amount, you need to enter the card details and click on "Pay now" to make the payment.
To make sure that you do not run out of credits in the middle of your campaign, you can enable the Auto-recharge option.
Note: This option will be visible after recharging your account. You need to recharge your account once to save the card.
Here, you can select the credit threshold that you want your card to be recharged and the amount of the charge.