In a further segmentation of the fledgling wireless market, Wells Fargo & Co. has launched a mobile banking service targeting small-business customers.

The San Francisco company already offers mobile services for retail and corporate clients, and James P. Smith, an executive vice president and the managing head of its Internet services group, said that consumer adoption has topped bankers' expectations.

"This is really just the start of what we're doing," Mr. Smith said in an interview Tuesday, after the company unveiled the small-business service. "We believe consumers, small businesses, and large businesses all will develop their own unique set of features and functions that they will want to access while they're on the go."

The small-business service is based on the same technology as Wells' retail offering, but "the experience is somewhat different, because the needs of small businesses are more complex," he said. "Those owners often have personal accounts and frequently have multiple small businesses."

The new service lets business owners view account balances and transaction histories for deposit and credit accounts that they select and to transfer funds between Wells accounts.

In the future, Wells plans to introduce some features that are not available on the retail service, such as the ability to approve a payroll from a mobile device or to conduct transactions in foreign currencies, Mr. Smith said.

Owners who delegate the authority to use certain accounts to office managers or outside accountants will also be able to make those functions available to them, he said. Likewise, for owners who have separate businesses or separate sites, each with their own bank accounts, there are online safeguards that prevent the commingling of funds.

Wells has tested the service with business-owner customers, and though it is too early to gauge uptake among those customers, on the retail side "we are almost at the point where we expected we would be at the end of the year," he said. "It has exceeded our expectations not only in the numbers, but in persistent usage."

Wells had expected retail mobile users to access their accounts once or twice a month, but on average they are accessing their accounts about five times a month, he said. "I would say it's off to a promising start."

While most banks have focused their mobile efforts on their retail customers, Wells introduced the service first to corporate clients, announcing CEO Mobile in May that included some features from its Commercial Electronic Office cash management portal. The retail service followed in July. All of Wells' mobile services use the Web browsers in mobile devices, rather than text messaging or an application taht is downloaded into the device.

Wells is testing a mobile payment service in conjunction with Visa U.S.A., the San Francisco card company. A handful of Wells and Visa employees now have cellphones with integrated near-field communications chips that they can use for contactless transactions at the point of sale, and the companies have said they anticipate launching an expanded pilot with 300 to 500 consumers in the fourth quarter.

Red Gillen, a senior banking analyst at the Boston research and consulting firm Celent LLC, said Wells is trying to stake out a position as a leader in mobile banking through its segmentation strategy.

"They're indicating to the market that they are very serious about this," he said.

Much of the banking industry's mobile efforts have been focused on young consumers, such as Generation Y (those ages 18 to 25), Celent estimates that 30% of online banking households will be using mobile banking services by 2010, Mr. Gillen said. "It's not going to be limited to Gen Y, and it's not going to be limited to people with BlackBerrys and Treos."

Business owners probably will take up mobile banking quickly for tasks such as making purchasing decisions at the point of sale, he said. "In some ways, it's very relevant to this demographic, because they are often out in the field."

Mr. Gillen said he has been using his cell phone for banking functions, such as when he is getting ready for weekend shopping. "I use that thing an awful lot to check the balance on the account to which my debit card is tied. I love it."