She said, "I don't need to find an ATM or a computer to know what's going on in my bank account."
Consumer Reports money adviser Greg Daugherty says banking on a cell phone is like having an ATM in your pocket.
"Text banking can be done with the simplest of phones," Daugherty said. "You send messages to get your account balances, and you get text messages when your balance is low or when your withdrawals or deposits are posted."
If you have a smart phone, like Katy, or a tablet computer, you can transfer money and pay bills, too.
Daugherty explained, "There are also banking applications designed specifically for your bank and model of phone. Chase, for example, will let you take a picture of your check with your camera phone and deposit it."
But you do need to make sure your banking on the go is secure.
"Never do mobile banking on a public Wi-Fi network," Daugherty advised. "When you're on your bank's website, always look for the little lock symbol in the browser to know that you're on a secure site."
It's also a good idea to install security software. That way you can safely join Katy and 39 million other Americans who already do mobile banking.
"I know exactly what's in my account, when things have cleared, you know, when money is coming out. I feel very on top of my finances," Katy said.
Along with the convenience, Consumer Reports money adviser says there's another plus with banking on your cell phone. Banks typically don't charge extra fees for this service -- at least not yet.