First it was the tellers. Now, call centers are under threat as financial services firms weigh new voice-activation technology to cut the cost of customer service.

USAA, GEICO Corp. and other financial firms are turning smartphones into virtual clerks. USAA in February became the first to let depositors use its mobile application via spoken commands. Now, Wells Fargo, U.S. Bancorp and ING Groep also are among about 50 firms working with Nuance Communications Inc. to use similar technology in mobile apps.

While banks have offered basic services over the phone for years, new programs seek to provide more complex interaction, similar to Apple’s Siri talking digital assistant, also powered by Nuance’s voice and artificial-intelligence software.

Customers will eventually be able to ask, “Has my check cleared?” or “Am I on track to save for retirement?” using apps, instead of visiting a branch or dialing a call center.

The feature lessens the need for human interaction and could reduce the number of customer calls to banks by as much as 40 percent, said Richard Crone, chief executive officer of researcher Crone Consulting.

By using voice-based apps to cut the number of call centers and workers to staff them, the financial-services industry could save $8 billion to $12 billion a year, he said.

“There’s a business case around reducing call-center calls,” said Dominic Venturo, payments chief innovation officer at U.S. Bancorp, which tested voice banking with hundreds of its own employees earlier this year.

While apps vary from bank to bank, a user can typically activate the tool with a button and then start asking questions. The software bases its response on a quick review of such information as the customer’s account and banking history, providing answers with text or spoken word.

The overhaul of banking apps was prompted largely by Nuance’s release in August 2012 of Nina — a Siri-like virtual assistant designed for mobile apps. Using artificial intelligence and a dictionary of thousands of banking-related phrases, Nina can simplify finding answers to complex financial queries on the go, said Robert Weideman, an executive vice president at Burlington, Mass.-based Nuance.

“We are seeing something very similar to mobile-check deposit — all of a sudden, everyone is doing it,” Weideman said.

The market for voice-recognition technologies will reach $113 billion in 2017, up from about $53 billion last year, BCC Research estimates.

In two to three years, mobile will account for more than half of all industry customer-service interactions, up from less than 30 percent today, according to Crone.