Lisa Kluever doesn't have much time for personal banking. Even if she had time during her 12-hour workdays at a finance company in California, she wouldn't use her office's Internet connection to do banking.But in November, Kluever signed up for a service that her bank, San Francisco-based Wells Fargo ( WFC), began offering this summer. Now Kluever uses her BlackBerry Pearl to watch her checking-account balance whenever she wants, typically during her morning commute. Kluever's phone has helped on many occasions. Once, a friend bought her a ticket to Hong Kong in December so they could sit together on the trip. She was able to send him the $950 she owed him quickly, since she'd already invited him to join her mobile-banking network. "It was easier to use my phone that way than to call Wells Fargo," Kluever says. Officials have long dreamed about such mobile banking, when cellphones perform tasks ranging from stopping check payments to providing stock quotes to transferring foreign money. Now, banks such as Charlotte, N.C.-based Wachovia ( WB) and Bank of America ( BAC) as well as Seattle's Washington Mutual ( WM) have been scrambling in recent months to make such services real. Experts are cautiously optimistic. "In the 2000 to 2003 time frame, consumers found it hard to get services that functioned as promised, so utilization was low," says Ed Kountz, senior analyst for payments at Jupiter Research. "That's changing. We're seeing things now that are more promising in terms of sophistication." The change takes place amid the expansion of data networks and advances in cell phone technology. Meanwhile, companies have more potential customers; according to the trade group CTIA, more than 243 million people subscribed to cell phone services in 2007, compared with about 135 million just five years ago.