BoA introduced Web-based mobile banking services in March to online banking customers in selected markets. The bank expanded the service across the US in May.

Subscribers to the free service can use their mobile phones and smartphones when they're on-the-go to check account balances, pay bills and transfer money.

The service is accessible to consumers who have mobile Internet access via their service provider.

Commenting on the 500,000 customer milestone, Lance Drummond, e-commerce and ATM executive at BoA, says: "We're thrilled with the initial customer response and expect this trend to continue as more people discover the convenience of accessing their accounts while on-the-go."