Originally Posted by Lensman

From Citibank:

"Virtual Account Numbers is a free service for Citi® cardmembers that gives you a substitute card number to use in place of your credit card number when you make a purchase online. This random number provides you with additional security.

It's easy to use: before every online purchase, you simply get a new number from Virtual Account Numbers to use at each new merchant. And activating this free service is easy..."

So bascially, no long-term rebills.