WASHINGTON — Property manager Joshua Rosenthal was in a car headed toward Miami Beach when he realized he needed to transfer a tenant’s rent money to his company’s account. No problem. The driver didn’t even have to pull off the road. Rosenthal, the owner of property-management company CAPM, just fiddled with his PDA, and the job was done.

“When you’re away, problems seem to accumulate at a higher rate … than when you’re present, so I live off of this,” he said, motioning to his PDA, which sat next to him on a couch in a D.C. coffee shop. “Connecting to my bank is a convenience.”

Mobile banking — that is, checking an account balance, transferring funds or paying a bill using a cell phone, BlackBerry, PDA or iPhone — is still in its infancy, but it’s gaining momentum. About 3 million people used mobile banking in the past 90 days as of June. That was almost triple the number of people who used it six months before, according to TowerGroup, an industry research firm. But the number of mobile banking customers is tiny compared with that of customers who use online banking services from their computers. For example, Bank of America has 1.2 million mobile banking users. That’s less than 5 percent of its online banking customers.

Mobile banking must overcome some hurdles before it can be widely adopted. Many consumers worry about security risks. Mobile banking software — still in its 1.0 form — has to work more seamlessly before the service can be very convenient. Accounts can be tedious to set up, and bank information can load slowly (at least by today’s instantaneous standards). Sometimes, customers must log out to use some services, such as finding an ATM, and then log back in if they want to continue banking. There’s also competition from other electronic services. Account information is already easily accessible online, at ATMs and over the phone.

Different approaches

A number of banks, including Citibank, offer mobile banking through downloads available only to customers who have specific carriers and phones. Other banks, including Bank of America, Wachovia and U.S. Bank, offer a slimmed-down version of their online banking systems for mobile customers. It can be accessed by anyone with a phone capable of going online. Clients log on and use links to check their balances, transfer funds, and in some cases, pay bills.

Other banks offer a uniquely mobile solution: Chase customers who text-message “BAL” to Chase (24273) on their phone quickly receive a reply with their account balances. Customers can also check transaction histories and get due dates for credit card payments.

Some banks are working on integrating all three solutions. Citi and SunTrust both plan to offer all three mobile banking options to their customers sometime next year.

Banks say mobile banking offers customers an added convenience that they can’t get using online banking or an ATM.

“We recognized that customers want convenience, where they want it when they want it,” said Peter Knitzer, the chief executive of Citibank North America. “We wanted to make it more accessible for customers to get to their money and move their money.”

Is it safe?

Mobile banking is more than an extension of online banking, said Mark Schwanhausser, a research analyst at Javelin Strategy and Research. “If you view mobile banking as just simply another version of online banking, you’re missing the opportunity to see what it is,” he said. “There are times when you want to check your money, whether you’re in a taxi, on a mountaintop, or in line at the cash register. It’s not yet mainstream, (but) it’s one of those things that’s going to be the Holy Grail.”

Maybe. But first banks will need to prove that it’s safe.

Most consumers polled said they were concerned that their personal information could be compromised by hackers or if they lost their phone, according to Javelin’s research. And consumers aren’t the only ones worried. Of the 13 mobile banking vendors polled by Javelin, 10 cited security fears as among the biggest hurdles keeping them from building their mobile programs.

There haven’t been any major attacks in the United States.

People in other countries have seen “nuisance” banking attacks similar to online phishing schemes, said Bob Egan, chief analyst and managing director of TowerGroup. In a typical attack, a fraudster would send a text message with a link to a bogus mobile Web site that looks like a bank’s. The site would ask for log-on, account or other personal information. The attacks can eat into users’ text-message plan limits, but, “in general, people so far have been smart enough to ignore them,” Egan said.

As mobile banking grows, it will probably become more attractive to scammers, experts say. “Mobile banking is the next unexplored wilderness from a fraudster’s perspective,” said Joram Borenstein, a senior product marketing manager for the Identity and Access Assurance Group at RSA. RSA, which monitors the “fraudster underground,” has seen an uptick in hackers’ chat room discussions about mobile banking attacks.

But, Borenstein said, banks are working to protect customers from attacks. “From our experience, the financial institutions are being very proactive about this, both for themselves as businesses and for their consumers.”