Verizon Wireless, AT&T Inc. and T- Mobile USA plan to invest more than $100 million in their joint venture that lets consumers pay for goods with mobile phones, Bloomberg said.

The investment sets up a showdown between the venture, known as Isis, and rivals such as Google Inc., which has set up a mobile-payment service. The amount of funding depends on how successful Isis is at attracting banks and merchants, a person who asked not to be identified told Bloomberg.

The carriers have created the alliance to grab a piece of the market for mobile commerce, which lets consumers buy things by tapping devices against a reader at checkout. The market could reach $670 billion by 2015, according to Juniper Research Ltd.

The carriers could invest hundreds of millions of dollars in the venture if it gains followers, one person said, helping it catch up with Google, which unveiled its own mobile-wallet service in May.

“Over the long haul, operators have to create new businesses that derive value from more than access,” Chetan Sharma, an independent wireless analyst, told Bloomberg. “It’s a given that people are going to be transacting more over cellphones. It could open a potential new revenue stream for them.”

Worldwide mobile payments will generate $240 billion this year, growing to two to three times that amount within the next five years, according to Juniper Research, Bloomberg reported.