Normally, activating a credit card takes just a few minutes and requires customers to make a phone call, log into an online bank account, or activating the card through an ATM machine using the assigned PIN number, according to CreditCards.com. Activation ensures the authorized user has the card.
Credit cards often arrive in the mailbox with a sticker directing the cardholder to call and activate it before use. However, CreditCards.com indicates that some card issuers allow charges to go through without activation as a courtesy to the customer. In some instances, the issuer limits the number of transactions before requiring activation.