One third of Bank of America customers — 17 million people — bank on their mobile devices, and the number is growing at a rate of 150,000 per month.

Yet customers have not given up more traditional channels. Ten million customers a week call one of the bank's contact centers; seven million walk into one of its branches.

Understanding that dichotomy is important, and many of the popular explanations for it are wrong, warns Steve Beasty, consumer banking technology executive.

"We all [assume of] people walking into the branch, 'That's my mother,' while the digitally active customers are like my 20-year-old daughter," he said. "But when we dig into this deeper, that's not what's going on. The digital customers are doing basic transactions online and on mobile — checking balances, depositing checks. But they're also using our physical branches and our call centers when they have a concern about something in one of their accounts or they've got a problem — 'I tried to deposit a check at the ATM and it shredded my check.' "

Other times these customers are looking for advice, perhaps to help choose a mortgage.

Beasty's team is working to smooth the experience as customers cross from the digital to the physical outlets of the bank. "They come to the branch or contact center to finish something they started in mobile," Beasty said.

His first goal is to make the transition effortless. "Digital customers don't want to have to type in numbers or information," Beasty said. "We just want to click, tap or swipe. So it needs to be pretty automatic."

The second goal is for customers only to have to authenticate themselves once.

"We do it differently in each channel. In the ATM, it's a PIN. It's security questions in the call center. It's a password to get online," Beasty said. "Once that customer has come through those doors, we don't want to make them go through that again."

The third element of the ideal cross-channel experience is understanding and recognizing what brought the customer from a digital channel to the branch or call center.

"What were they doing, or what did we do to them?" Beasty said. "Say their account got hit with a fee last month. We have to look at that and turn it into insight for that employee in the branch."

The bank is creating specific "connected experiences" in the effort to meet those goals.

One is a "Click-to-Dial" feature for preferred banking customers. They will tap a button in the mobile banking app and get connected to a specialist in the call center.

The specialist does not have to ask any security questions and can see what the customer was doing in mobile banking.

"So rather than starting with 'Who are you and what do you want?', it's 'Welcome to Bank of America, Mr. Beasty. We see you were reviewing your credit card data in your mobile banking application. Is there something there I can explain?' [It is] a much smoother transition and experience for those customers."

In a second example, the bank is letting call center specialists see the customer's online banking session in real time, so they can guide customers by phone.

And, off-site tellers who communicate with customers through the banks' ATMs can remotely control the ATM, for instance, by lighting up the card reader when the customers need to swipe. The bank has about 500 such "ATM withTeller Assist" machines in 200 locations.

Like Wells Fargo and Wintrust Financial have done, B of A is considering whether to build connections between its mobile apps and its ATMs, to let customers pre-stage ATM transactions that they can complete when they get to a machine. It also might create a mobile banking feature that would let customers order cashier's checks they could pick up at the branch when ready.

In one big technology project, Beasty's team is taking the 13 different interactive-voice-response systems the bank has acquired over the years and merging them into one.

And in one of its branch-transformation projects, Bank of America has equipped the staff in about 2,000 financial centers with iPads and Samsung tablets.

"Now with a swipe of a card, the branch people can see all the information about the customer, the accounts where you bank with us, whether or not you have cases open with us," Beasty said. "Their job is, now that I know who you are, how can I help you and how can I get you to the expertise you need." Staff members are becoming more specialized, focusing on mortgages, small business and such.

When customers come in to do routine transactions, the relationship bankers in the branches are trained to show the customer how to do them at a self-service kiosk, standing next to the customer.

"After a few times, they'll want to do it themselves," Beasty said. "Then the relationship manager can focus on things that create value."

Beasty also shared a few new technologies on his drawing board.

One, which the bank expects to roll out soon, is called "virtual hold."

"In the call-center experience, when you hear the wait time is 10 minutes, that's ten minutes of your life you're never going to get back," he said. In virtual hold, when the time gets beyond five minutes, the system offers to call back customers when their turns in line come up.

"It seems simple, but [it] could make a big difference for customers," Beasty said.

Another possibility is related to the bank's fraud alerts. It could let customers turn their cards off and on in a variety of circumstances. For instance, users might ask that their cards be turned off when they spent $100 on Starbucks in a given month. The card could be turned off by a customer who thinks he may have lost or misplaced his wallet.