Bank of America (BAC) has passed a mobile banking milestone.

More than one million small business customers are using the Charlotte, N.C., bank's mobile banking application, it announced Wednesday. The app lets small business customers manage their accounts, pay employees and suppliers, set up bill payments and track transactions, and is available on the iPhone, iPad, Android, BlackBerry and other mobile devices, the company said.

"The number of small businesses now using Bank of America's Mobile App is a testament to today's growing demand for better integration of technology and greater online, mobile and self-service banking options," said Marc Warshawsky, B of A's digital product executive.

B of A also announced that it ranked first in an annual study of small business online banking conducted by Keynote Systems, a firm that tests companies' online systems. B of A received the highest overall score and was ranked first in three categories: functionality, ease of use and privacy and security.